Pollen of Nigerian Plants

Grana ISSN: 0017-3134 (Print) 1651-2049 (Online) Journal homepage: http://www.tandfonline.com/loi/sgra20 Pollen of Nigerian Plants M. Adebisi Sowunmi To cite this article: M. Adebisi Sowunmi (1995) Pollen of Nigerian Plants, Grana, 34:2, 120-141, DOI: 10.1080/00173139509430002 To link to this article: https://doi.org/10.1080/00173139509430002 Published online: 01 Sep 2009. Submit your article to this journal Article views: 691 View related articles Citing articles: 30 View citing articles Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalinformation?journalcode=sgra20 Download by: [37.44.199.42] Date: 21 November 2017, At: 23:10

Grana 34: 120-141, 1995 Pollen of Nigerian Plants II Woody Species M. ADEBISI SOWUNMI Downloaded by [37.44.199.42] at 23:10 21 November 2017 Sowunmi, hl. A. 1995. Pollen of Nigerian plants. 11. Woody species. - Grana 34: 120-141. ISSN 0017-3 134. Pollen grains of 40 Nigerian woody species which are among the ecological indicator species of forest and savanna vegetation communities are described and illustrated with both Lhl and SEhl micrographs (37). Where appropriate, observations made here are compared with those of some earlier investigators. Eight species were di- or polymorphic with respect to aperture number. The use of SEhl greatly enhanced the characterisation and interpretation of pollen morphological features. particularly where these features were indistinct or not detectable in Lhl. This second part of the series on the pollen flora of Nigeria. as was the first, is expected to be useful in plant taxonomy, Quaternary palaeoccology and petroleum exploration as well as in archaeological research and the honey industry. Sowriiiiiii, hi. Adebisi. Deparfriterrr of Archaeology arid Arir/iropology, Universify of lbadan. lbadan, Nigeria. (Accepted 25 Noveiiiber 1994) After a considerable time lapse, the second in the series on the pollen flora of Nigeria is presented, the first part having been published by Sowunmi in 1973. The pollen grains described here are those of some other woody species characteristic of forest and savanna vegetation, Two main objectives for embarking on a composite and detailed description of the pollen of Nigerian plants were stated in the first publication, i.e. to provide both additional taxonomic parameters and an essential reference for the identification of fossil pollen in Quaternary deposits (Sowunmi 1973: 145). However, such a compilation, accompanied by photographs taken with both light and scanning electron microscopes (LM and SEM, respectively) - a type of pollen atlas - is also of immense value in several other fields of study and in certain industries. In petroleum exploration, where the modem trend is to adopt the methods of Quaternary pollen analysts (Poumot 1989), which include the identification of the botanical affinity of fossil pollen, a pollen atlas is an essential tool in palynofacies studies through which depositional palaeoenvironments can be reconstructed. There is a great demand now for such a pollen atlas in the Nigerian petroleum industry. A Nigerian pollen atlas would facilitate the establishment of the botanical and geographical origins of Nigerian honey for application in a commercially viable honey industry that is as yet in its infancy (cf. Sowunmi 1976, Agwu & Akanbi 1985); furthermore as pointed out by Sowunmi (1976), in the tropics where insect pollination is said to be predominant, the pollen analysis of fossil honey samples from archaeological sites could complement the more conventional pollen analytical study of fossil sediments in providing important data on ancient environments and cultures. Finally, there is abundant evidence for the importance of fossil pollen data in shedding light on the subsistence economy of ancient peoples, the impact of the environment on them and the anthro- pogenic changes they themselves caused in the landscape (see Dimbleby 1985, Sowunmi 1988 for reviews). A pollen atlas is, of course, a fundamental reference for the identification of fossil pollen. The use of SEM for most of the 40 species studied here greatly enhanced the chancterisation and interpretation of their pollen morphological features, especially those which were obscure or undetectable in LM. As in the first part of this series, comparisons have been made of the pollen features observed here with those recorded by other authors who have described a few of the species. MATERIALS AND METHODS All but two of the pollen samples used in this study were obtained from the herbarium of the Royal Botanic Gardens, Kew. England (K); of the two exceptions, one. (Conibrerrrm receiiiosrtiii) was fresh material from Ibadan, and the other (A//oplij//irriz afrcanrrs), was herbarium material from the Forestry Research Institute of Nigeria. Ibadan (FHI). The pollen samples were all acetolysed following the standard technique (Erdtrnan 1966). Those for Lhl study were mounted in glycerine jelly, the slides were sealed with paraffin wax and the examination carried out using a Nikon Labophot microscope, while photograps were taken with a Nikon 35 mm camera, all x 1000. Ten to 20 grains were measured, but where it was not possible to measure up to 10, the figures were prefixed with ca. For SEhl, the acetolysed pollen was dehydrated successively in 70% and 95% ethanol, and a few drops of a mixture of the sample and 95% ethanol were air dried on specimen stubs and coated with platinum; the stubs were examined with a Hitachi S-510 SEhl. The pollen terminology follows Jackson 1921, Erdtman (1966) and Faegri & Iversen (1975). Nomenclature follows that of Hutchinson & Dalziel (195-2-1968) with subsequent changes as compiled by Lowe & Soladoye (1990). Crana 34 (1995) @ 1995 Scandinavian University Press. issn 0017-31U

Polleir of woodj Nigerian plants 121 Fig. 1. Anacardiaceae. A-G. Aritrocnrjori rizicraster. (D-E) x 2000. (F, G) x 8000. (G) superficial vermcnte processes. H-hl. Lnrir~eo egregia. (J, K) x 3000. (L, hl) x 8000. (hl) densely spaced sexinous elements in colpus membrane. A, B, C, H, I - Lhl x 1000. POLLEN GRAIN DESCRIPTIONS Anacardiaccac Antrocoryoti iiiicraster A. Chev. & Guill. Nigeria: Sapoba. Kennedy 16631K (Fig. 1 A-G). Size. p: 29.2 pm (26.5-32.0 pm), E 26.6 pm (24.0-27.0 pn). Exine thickness 1.6 pi, 2.7 pm at the apertures as seen in polar view; thc tectum, baculate layer and nexine are all of equal thickness. Sliape- - Prolate spheroidal to subprolate, mostly prolate spheroidal, P/E 110-1 19; amb goniotrcmc, sides straight or sometimcs slightly convex. Apcrriircs. - 3-colporate. Colpus 24.9 lini long, 2.0 Iim wide for most of its length, wider around and at the equator 9 Graita 34 (1995)

Fig. 2. Anacardiaccae. A-E. hrrirea ~rehdsclzii. (D) x 3000. (E) x 8000. Annonaccae. F-L. CleisrrqJIrolis pr~lens. (El) seemingly 3-slit colpus. (K) x 3000. (L) orbicules and smooth euinc, x 8000. hl-q. Ifcs~loD~~s crispifrm/s, (hf) cornpositive micrognph, left half - pattern in distal face, right half- optical cross scction. (N) pnttcrn in proximal face, (P) pattcni in proximal Face, x 6000. (Q) pattern in distal face, x 6000. (0) x GOO. A, B, C, F, G, 11, I, I, hl, N - LA1 x 1000.

Pollen of woody Nigerian plants 123 Downloaded by [37.44.199.42] at 23:10 21 November 2017 Fig. 3. Apocynaceae. A-D. Hitnteria nirida. (D) exine pattern. x 6000. E-J. Rawolfia caffm. (G) subpolar view. note cavity adjacent to colpus. (F) subequatorial view. (H) x 2000. (I, J) x 5000. surface pattern, note cavity. A, B, C, E, F, G - Lhl x 1000. where the maximum width is up to 4.4 Iim, rnargo 1.0 Iim thick, distinctly thick at the os, membrane with densely spaced sexinous elements; 0s markedly elongated laterally, polar length 4.7 Iim, width 11.3 pm. Apocolpium diameter 6.3 Iim. E.riwe. - Subtectate, slightly undulating, finely striate to striato-reticulate, in SEM lirae have irregularly spaced, apparently superficial verrucate-like processes which traverse the very narrow striae in parts, producing a striatoreticulate image; lirae 1.0 p i or less wide, supported by one to two rows of barcules. Lniiiica egrcgin Engl. & K. Krause: Ijaiye F. R. Rose 101 (Fig. 1 H-M). Size. - P: 27 pm (26-29 pm), E 25.2 I'm (23.5-265 pm), Exine thickness 2.0 pn, tapering sharply towards the apertures. Slzope. - Prolate spheroidal, P/E 109-1 11; amb peritreme. Apertures. - 3-colporate. Colpus 22.5 Iim long, 4.5 pi wide, tapering abruptly to a point at the ends, very thin granular margin sometimes visible, membrane with densely spaced sexinous elements; 0s f isodiametric, 9.3 Iim wide, with a distinct annulus. Apocolpium diameter 5.4 Iim. Erjne. - Subtectate, undulating, stratification distinct, finely striate, in SEM lirae have irregularly spaced, apparently superficial processes but not as pronounced as in Antrocorjon rriicrmta'; lirae 1 Iim or less wide, bifurcating, closely interlocking, supported by one to two rows of bacules. L. i,uhc.itsc/iii (Hiern) Engl. Nigeria: Osun F. R. Gilman 520, (Fig. 2 A-E). Size. - P 22.7 pm (21-24.5 pm), E 21.9 Iim (19.5-24.5 pm). Exine thickness 1.8 pm, tapering sharply towards the apertures. Slinpe. - Prolate spheroidal, PIE 100-108; amb peritreme. Apcrtirres. - 3-colporate. Colpus 18.2 Iim long, 4.4 Iim wide, tapering abruptly at the ends. Very thin granular rnar- 9* Graria 34 (1995)

124 M. A. Soic irrziizi Downloaded by [37.44.199.42] at 23:10 21 November 2017 gin sometimes visible as in L. egregin, colpus membrane as in L. egregin; 0s indistinctly demarcated, seems longitudinally elongated, in sharp contrast to the situation in L. egregin, annulus thin, granular. Apocolpium diameter 4.9 I m. Exine: - Subtectate undulating, stratification distinct, finely striate, in SEM the irregularly spaced verrucate processes on the lirae are as pronounced as those in Awtrocar~on iiricroster; lirae up to 11.5 pm wide, closely interlocking as in L. egregin, supported by one to three rows of bacules. Both L. egregin and L. ivelwitscii are basically similar to L. itzocrocnrp described by Sowunmi (1973). except that no syncolpate grains were found in the former two species. Annoiiaceae Cleistopholis pareiis (Benth.) Engl. & Diels, Nigeria: n. Oyo. Richards 5052 (Fig. 2 F-L). Size. - P: 17.9 Itm (14-23 pm), E,: 34.9 Itm (32-37 pm), E2: 20.1 iim (17-26 Iim). Exine thickness 0.8 iim. SIznpe. - Elliptical in polar view; bean-shaped in shorter equatorial view, boat-shaped in longer equatorial view. Apertirre. - I-colpate. Position of colpus not known for certain as no tetrads were seen. Colpus 28.4 iim long, 5.8 Iim wide throughout its length or gently tapering towards the ends, outline often wavy; margo 0.8 pn thick, granular; some grains seem to have a three-slit colpus (3.7% of 81 grains). Exiize. - Tectate, smooth, supratectal orbicles present, mostly rounded in shape or irregular in outline, each with a dense cover of minute vemcae as seen with SEM. Hexnlobirs crispiji oriis A. Rich., Nigeria: Lagos. Foster 41 (Fig. 2 M-Q). Size. - Tetrad: 83 pm x 90.4 Iim (77.5-91.5 x 84.0-102.0 [im). Individual grains P: 38.1 Iim (3247 pm), El: 58.8 [im (52-66 pm), Ez: 48.4 [im (46-52 pm). Exine thickness 3.8 Iim; tectuni 1.7 p i, baculate layer 1.2 pm and nexine 0.9 Iim thick. Sknpe. - Tetrads tetragonal or rhomboidal; grains in rhomboidal tetrads may be in one, two or three planes of focus. Individual grains: polar view f elliptical or rounded triangular, boat-shaped or rounded triangular in the longer equatorial view and kidney-shaped in the shorter equatorial view. Aperttrre. - Proximal leptoma of variable size and no definite shape, occupies most of the proximal face. Exiiie. - Subtectate, coarsely verniiculate to scrobiculate, more coarse on distal than on proximal face; muri markedly curved, 0.6-1.8 pin wide on proximal face, 1.O-2.0 Iim wide on distal face, supported by one to two rows of very distinct bncules as seen in LM, but SEM showed muri studded with minute verrucae of varying size, distal face being more densely verrucate. - N. B. SEM pattern very different from that of H. niorioprtnliis, but similar to that of Astermitlie nsterins with respect to dense cover of minute ven-ucae (cf. Le Thomas 1974: 53-55). Apocynaceae Hialterin riitida (Stapf) Th. & H. Dur. Nigeria: Ibadan F. R. Arboretum. Onyeachusim 48005 (Fig. 3 A-D). Size. - P: 38.7 pm (35.542.0 pm), E: 43.2 11 (40.0-46.5 ym). Exine thickness 1.5 ym at poles, 2.1 Iim at apertures. Slznpe. - Oblate spheroidal, P E 89-90; amb peritreme. Apertirres - 3-colporate. Colpus short and wide, 16.9 Iim long, 7.5 [im wide, tapering only very slightly at ends, outline often not distinct; 0s very large and markedly laterally elongated, tapering very sharply to a point at ends, polar length 6.8 Iim, width 21.5 Iim, with a thick margin distinctly stratified like exine, thickness 3.5 Iim, membraneous in non-colpal parts. Apocolpium diameter 25.7 I m. Exiize. - Subtectate, finely verniiculate to minutely reticulate, markedly undulating; in SEM, tectate with very minute though deep depressions of verying shape - rounded or narrow and linear or curved - resulting in a convoluted surface. Rnrrvolfin cnflrn Sond. Nigeria: Zaria district, n. Auchang. Dalziel 358 (Fig. 3 E-J). Size. - P: 36.3 kim (33.5-38.0 pm). Exine 1.5 pm thick in inter-apertural regions, 3.5 pm at apertures. Slinpe. - Oblate, PE: 70-72; amb goniotreme, sides straight to slightly convex. Aperttrres. - 3-colporoidate. Colpus relatively short, 10.5 Iim long, 5.0 [im wide, tapering sharply to the ends, margo distinct, 5.0 prn wide; on either side of each colpus is an elongated cavity as in R. voniitoria; this cavity, 4.6 pm wide, deeply cleaves the margo and seems thinly membraneous; in some grains, one cavity each of adjacent colpi are united to form a ring-like structure which may not always be as distinct as that found in R. voiiiitorin (Sowunmi 1973, pl. 1:8); 0s not visible in equatorial view. Apocolpium diameter 10.7 iim. fibre. - Subtectate, finely reticulate to smooth in mesocolpium but very coarsely so in apocolpium; in SEM, appears tectate, faintly fossulate, with scattered, minute perforations as well as very tiny verrucae which are more densely spaced at the apocolpium. - N. B. The grains of this species are very similar to those of K. voitritorin described by Sowunmi (1973) and by Fredoux (1974), but are smaller in size; furthermore, no 4- colporate grains were found in the sample studied here as was recorded for R. voiizitorici by Sowunmi (1973). - Corrigeiidiriir (in respect of R. roriiitorin as described by Sowunmi (1973): Grains not syncolpate; apocolpium diameter ca. 20.0 Iim. colpus ca. 48.0 Iim long, ca. 0,9 Iim wide, tapering towards poles; 0s polar length ca. 10.0 pm, width ca. 0.8 Iim, not always clearly visible in equatorial view. Bignoniaceae Kigclia nfricnizn (Lam.) Benth. Nigeria: Cross Riv. Division. Holland 238 (Fig. 4 A-B). Grotto 34 (1995)

Polleri of woodj Nigeriori plotits 125 Fig. 4. Bignoniaceae- A-B. Kigclin nfricuna. C-G. Srcrcoq~crinunr hifliinriimi. (F) X 1500. (G). bacula within Iumina, x 8000. Bombacaceae. (H), 1. Adulnrnoriin digifafcz. (11). composite micrograph, upper part - optical cross section, lower part - surface view of exine, x 8000. (I) reticulate exine and supratectal verrucae, x 8000. A, B, C, D, E, H - Lhl x 1000. Size.- P: 57.4 iim (52.0-61.0 pi), E: 48.3 pm (42.0-52.0 pm). Exine 2.5 pm thick, stratification distinct, tectum 1.2 itm, baculate zone 0.8 Irm, nexine 0.5 pm thick. Slzcrpe. - Subprolate, P/E 117-123; amb peritreme. Apertiircs. - 3-colpate. Colpus 48.3 pi long, 9.1 p i wide, tapering at ends, margo 2.0 pm thick, but not visible in all grains, colpus membrane very thin but granular. Apocolpium diameter 18.3 pm. Grarra 3.1 (19951

126 M. A. Soininnti Fig. 5. Burseraceae. A-D. Cariariirm sclnreinfctrthii. (C) x SOOO. E- 1. Dacryodes edttlis. (G) x 3000. (H) note granular colpus membrane x 6000. I-hl. Saritiria trinieriu. (L) x 3000. (hl) granular colpus membrane and tiny supratectal processes, x 8000. A, B, E. F. I, J, K - LhI x 1000. Exirze. - Subtectate, coarsely reticulate, heterobrochate, being finer at apocolpia than at mesocolpia; at mesocolpia muri 0.8 Iim and lurnina 3.3 pm wide, at apocolpia niuri 0.5 tipi and lumina 1.6 [irn wide; bacules within lumina, rnuri supported by one to two rows of bacules. Stereosperiiiirnt kirtttltianioii Cham. N. E. Cameroon. Hepper 3992 (Fig. 4 C-G). Size. - P 36.8 Iim (36.5-37.0 pm). E 32.0 pm (31 2-32.5 Iim). Exine 1.9 Iirn thick in mesocolpia, thinner towards poles, stratification distinct, tecturn, baculate layer and nexine about same thickness. Shape. - Prolate spheroidal to subprolate, P/E 114-1 16; amb peritreme. Apertures. - 3-colpate to 3-syncolpate. Colpus 3 1.5 pm long or extending to either one or both poles; owing to apolcolpia being very narrow (or absent in syncolpate grains) grains separate easily into three sectors; CO~PUS 65 pm wide at equator, tapering sharply towards poles, margo 1.0 pm Grorin 31 (1995)

Polleri of woody Nig'ericin plnrits 121 Fig. 6. Caesalpiniaceae. A-G. H~luderzdro~~ gabunense. (E) x 3000. (F) x 2000. (G) exine pattern, x 8000. Chrysobalanaceae. H-K. Puririari excelsu. (I) note thick margo. Combretaceae. LP. Anogeissirs leiucmpits. (N) prominent 0s membrane, x 6000. (0) granular colpus membrane of central colpus. x 6000. (P) colpus (longer arrow) longer than orate colpus (shorrnrro~*), x 8000. A, B. C. D, H. I, J. K, L. hl- Lhl x 1000. thick. Apocolpium diameter 2.0 Itm; in SEM colpus seems narrow for most of its length, widening towards poles. Evilre. - Subtectate, reticulate, heterobrochate, finer at apocolpia than at mesocolpia; at mesocolpia muri 0.9 pm and lumina 0.3 pn to 2.0 pm wide, at apocolpia muri 0.2 pm and lumina 0.5 Itm wide; bacules within lumina; muri supported by one to two rows of bacules. Boiiibacaceae Ackrnsonicl digitntcl L. Ghana: Ada Junction. Morton 2083, (Fig. 4 H-I). Size. - P: 79.3 pm (72.0-83.5 pm), E 93.2 Itm (84.0-108.0 pn) -excluding processes. Exine 2.0 pm thick, ca. 3.7 pn thick at pores, distinctly stratified, tectuni 0.5 p, bacdate layer 1.0 pi, and nexine 0.5 Itm thick. Shop. - Suboblate, P/E 77-86: amb peritreme. Aperttrres. - 3-ponte. Pore diameter ca. 10.9 pm, with a distinct annulus ca. 2.6 pm thick. Grcirio 34 (1995)

128 AI. A. Soitwrrtii Exirie. - Subtectate, minutely reticulate to reticuloid, muri distinctly simplibaculate; with densely spaced supratectral verrucae, height 2.3 pn (1.8-2.8 pm), basal diameter 3.1 Iim (2.0-5.0 pi); bacula densely spaced below and between verrucae, partial tectuni formed by coalescence of tops of groups of few adjacent bacula (Fig. 4 I). - N. B. Erdtman (1966: 75), in a very short description of the pollen of this species based on an LM study, referred to these processes as spinules, cf also Nilsson & Robyns 1986, Fig. 16 J). Burseraceac Carrnrirrrti schwirlfrrrthii Engl.: S. Nigeria. Unwin 19, (Fig. 5 A-D). Size. - P: 32.7 pi (30.0-34.5 pm), E: 22.2 Iim (19.0-23.5 pi). Exine ca. 2.0 pm thick. Shape. - Prolate, P/E 147-158; anib goniotreme, sides straight. Apertures. - 3-colporate. Colpus 21.0 Iim long, 0.5 pm wide, margo 0.2 pi thick, membrane sparsely granular; 0s distinctly laterally elongated, polar length 1.O pi, width 6.8 prn, with a granular margin, ca. 1.O [im thick. Erine. - Tectate, appears minutely and faintly reticuloid in LM, but fossulate in SEM, with undulating, anastomosing and narrow ridges, and unevenly distributed, very minute verrucate processes. Dacrjocles erlirlis (G. Don.) Lam. Nigeria: Okomu F. R. Brenan 9104 (Fig. 5 E-H). Size. - P: 34.0 pi (31.O-37.5 pm), E: 24.0 pn (21.O-28.5 lim). Exine 1.6 pi in equatorial region, 2.7 Iim thick at poles. Shp. - Subprolate to prolate, P/E 132-148; amb peritreme. Aperfrrres. - 3-colporate. Colpus 24.0 Iim long, 3.2 Iim wide at and around equator tapering towards poles, margo granular, ca. 1.5 Iim thick, colpus membrane granular; 0s markedly laterally elongated, polar length ca. 2.8 Iim, width 11.2 pi, with granular margin, 0.8 Iim thick. Apocolpium diameter 10.3 pn. Evirre. - Tectate to subtectate, mostly fossulate and similar to Carzariirrri schweirlfrrrthii, but punctate in parts; in LM appears faqintly and minutely reticuloid. Saritiria trirtiera (Oliv.) Aubrev. Nigeria: Sapoba. Kennedy 2232 (Fig. 5 I-M). Size. - P: 24.1 pm (21.O-26.5 pm), E: 22.5 pin (21.O-24.0 p). Exine ca. 1.8 Iini thick. Shape. - Oblate spheroidal to prolate spheroidal, P/E 100-110 anib goniotreme, sides convex to straight. Apertirres. - 3-colporate (1.1% of 280 grains viewed 2- syncolporate, colpi appear joined only at one pole). Colpus 17.5 Iim long, ca. 1.5 Iim wide, margo ca. 0.9 pi thick, colpus membrane granular; 0s markedly laterally elongated, 1.9 pm long, 8.0 pi wide, margin granular, 1.0 Iim thick. Exirie. - Subtectate, pattern as seen in Lhl more distinct than in other two species of Burseraceae described above, tectum rather irregularly reticuloid, with short, narrow channels in parts; in SEM, exine surface undulating, finely punctate to striato-punctate, tectum provided with numerous, evenly spaced, very minute verrucate processes. Caesalpiniaceae Hjlodcrrdron gabirrierzse Taub. Cameroon: Limbe, Victoria Botanical Gardens. Maitland 609 (Fig. 6 A-G). Size.-P: 18.3 Iim (17.0-19.5 Iim),E: 19.8 Iim (18.0-21.5 pn). Exine ca. 1.5 Iim thick. Shape. - Oblate spheroidal, P/E 91-94; amb goniotreme, sides straight to concave. Aperfrrres. - 3-colporate. Colpus often not well displayed in equatorial view, ca. 13.8 pi long, ca. 1.5 Iim wide, constricted in equatorial region and may widen or taper towards ends, colpus membrane granular, margo 1.0 Iim thick, mostly smooth and fossulate as seen in SEM; 0s longitudinally elongated, polar length 7.5 pm, width 4.2 pm, diameter 4.5 pm. Apocolpium diameter 4.5 Iim. Exitre. - Subtectate, disinctly but minutely reticulate; pattern not visible at apoclopium in LM but punctate and fossulate in SEM. Chrysobalanaceae Paririnri excelsa subsp. holstii (Engl.) Graham. Zaire: Yanganibi. Graham s.n. (Fig. 6 H-K). Size. - P: ca. 28.3 Iim (24.0-31.0 pn), E: ca. 41.5 I'm. Exine ca. 4.2 Iim thick, tapering towards apertures, ca. 2.7 Iirn thick. Shape. - Oblate, P/E 81-95; amb goniotreme, sides straight. Apertures. - 3-colporote. Colpus ca. 24.5 Iim long, ca. 3.5 Iim wide, tapering to a point at ends, margo very distinct, relatively thick, structured like rest of exine, ca. 4.5 Iim wide; 0s longitudinally elongated with a prominently granular membrane. Apocolpium diameter ca. 3.5 pm. Exirre. - Subtectate, finely reticuloid to striato-reticuloid, surface undulating. Tectum ca. 2.8 Iim, densely baculate zone ca. 0.3 [mi, nexine ca. 0.6 pm, nexine ca. 0.5 pm thick. Coiiibretaccae Atlogeisstis leiocarpw (DC) Guill & Perr. Nigeria: Mengu F. R., Pankshin. Keay & King 37090 (Fig. 6 LP). Size. -P: 14.6 Iim (13.5-15.0 pi), E: 12.7 pm (12.0-13.5 pm). Exine ca. 0.6 Iim thick. Shape. - Prolate spheroidal, P/E 111-112; amb goniotrenie, sides very concave. Apertirres. - 6-heterocolpate, comprising three colpi and three orate colpi. Colpus (without 0s) ca. 1 1.8 Iim (1 1.O-13.0 ym) long, ca. 1.0 rim wide; colpus with 0s 11.6 prn (10.0-12.0 pn) long, ca. 1.5 [im wide; 0s laterally elongated, polar length ca. 2.9 prn, ca. 4.5 Iim wide, with prominent membrane. Gram 31 (1995)

Pollen of woody Nigerian plnnts 129 Fig. 7. Combretaceae. A-E. Coinbretctrn raceinomti. (C) colpus (short arrow) shorter than orate colpus (long arroiv), x 2000. D, E x 8000, orate colpus in (D) and not orate colpus in E. Ebenaceae. F-J. Diospyos iuespi/uorinis. ([I) (x 1500) (I) (x 8000) - granular colpus membrane. (J) exine surface pattern, x 8000. A, B, F, G - Lhl x 1000. Downloaded by [37.44.199.42] at 23:10 21 November 2017 Colpus without as long as or longer than orate colpus less deeply invaginated seemingly with a similar, marked exine thinning, and a very similar, coarse microstructure. Exine. - Pattern faintly striato-reticuloid in LM but appears tectate, finely fossulate to minutely foveolate in SEM, depressions very narrow and linear. ridges also very narrow, running in a somewhat parallel fashion, often interlocking, forming a striato-reticuloid pattern. Coiiibretiiiii raceniosiriii P. Beauv. Nigeria: Ibadan. Sowunrni 1189 (Fig. 7 A-E). Size.- P: 26.9 Iim (25.5-27.5 p), E: 21.6 pn (19.5-23.0 pm). Exine ca. 0.9 pm thick. Shop. - Subprolate, P/E 120-131; amb goniotreme, sides straight to convex. Aperttires. - 6-heterocolpate as in Airogeissirs leiocarps. Colpus ca. 17.4 pm long, 3.0 pn~ wide; orate colpus 22.8 [tm long, ca. 1.2 (?) Iim wide; 0s circular to longitudinally elongated, polar length 5.0-5.5 pm, width 4.0-5.0 pm, with prominent membrane. Colpus without shorter than orate colpus, with similarly marked exine thinning are less deeply invaginated but with a similar coarse microstructure. Exiize. - Subtectate, vermiculate to minuteley reticuloid as seen with LM, with SEM, foveolate to fossulate, depressions narrow and linear, surface undulating, ridges forming a distinct striate to striato-reticulate pattern. Ebenaceae Diospjros niespiliforrnis Hochst. ex A.DC. Nigeria: Jos Plateau, n. Panyam. Tuley 2271 (Fig. 7 F-J). Size. - P: 42.4 rim (39.046.0 pm), E 312 pm (27.0-33.0 pm). Exine ca. 1.4 pm thick. Grma 34 (1995)

Fig. 8. Euphorbiaceae. A-G. Alchornea cordifolia. (D) aberrant 2-colporate pollen grain. (E) x 3000. (F) x 4000, (G) operculum and exine pattern, x 8000. H-K. Atifidesnia retiowti. (J) x 3000. (K) granular colpus membrane and exine pattern, x 8000. LQ. Uapaca acirtttitiorn. (0) aberrant 4-colporate grain. (P) x 2000. (Q) supratectal spinules, x 6000. A, B, C, D, H, I, L, hi, N, 0 - Lhl x 1000. Shape. - Prolate, PE 139-144; amb goniotreme, sides straight to concave. Aperrrircs. - 3-colporate, colpus 33.9 pm long, ca. 3.7 Itm wide, conspicuously consticted in equatorial portions, as seen with LM, margo ca. 1.9 Iim thick, membrane coarsely granular; 0s markedly elongated laterally, ca. 3.4 Iim polar length, ca. 12.0 Itm wide, tapering sharply at ends, margin granular, ca. 0.4 Iim thick. Apocolpium diameter 9.3 pm. Grcmo 34 (1995)

Pollen of woody Nigerian plarifs 13 1 Fig. 9. Guttiferae. A-E. Allniiblockiofloribirrido. (C) x 1500. (D) exine surface pattern, x 8000. (E) orate colpus, x 8000. hleliaceae. F-hl. Coropn procero. (I) aberrant 5-colporate grain. (J, K) aberrant 3-colporate grains. (K, L) x 2000. (hl) granular colpus membrane and exine pattern, x 8000. N-R. Klqa grondifoliolo. (P) x 1500. (Q, R) granular colpus membrane, x 8000. A, B, F, G, H, I, J, N, 0 - Lhl ca x 1000. Euphorbiaceae Alcliorrzea cordifoh (Schum. & Thonn.) Mull. Arg. Nigeria: Kontagora. Dalziel 88, (Fig. 8 A-G). Size.- P: 19.0 Iim (21.5-23.5 pm), E: 21.3 pn (20.0-22.5 pm). Exine ca. 1.9 pm and ca. 1.6 pm thick at poles and mesocolpia, respectively, ca. 3.2 pn thick at apertures. Shape. - Prolate spheroidal, P/E 104-108; amb pleurotreme. Aperfiires 3-colporate, very rarely 2-colporate (less than 1% of 200 grains viewed). Colpus 17.7 Iim long, ca. 2.7 Iim wide, tapering sharply at ends, margo ca. 2.3 Ctm thick, pontoperculate; 0s laterally elongated, polar length ca. 5.6 }im, ca. 8.8 }im wide, membrane very coarsely granular. Grana 3-1 (I 995)

132 M. A. Soirwiznzi Fig. 10. hleliaceae. A-G. Kliojo scricgnlcrisis. (D) aberrant 3-colporate pollen grain. (E) x 1500. (F) exine surface pattern, x 8000. (G) granular colpus membrane, x 8000. hlimosaceae. H-P. AlOizia arliarithifolia. (H) four cells from polyad, note optical cross section. (I) polyad. (J-hl) single cells, note pores. (N) polyad, 12 og 16 cells displayed, x 1000. (0) single cell from polyad, x 3000. (P) tectum fissured into blocks supported by stout bacula and with tiny supratectal processes, x 8000. A, B, C, D, H, I, J, K, L, hl - Lhl x 1000. Apocolpium diameter 5.5 iim. Exiize. - Subtectate, punctate to vermiculate; with SEM surface finely and evenly convoluted, very finely punctate to vermiculate. Antidesiiin veiiosiiiiz Tul. Nigeria: Kontagora. Dnlziel 389. (Fig. 8 H-K). Size.- P 27.4 p i (25.5-29.0 Iim), E: 16.0 pm (15.0-17.5 pm). Exine ca. 1.3 ym. Shape. - Prolate, P/E 166-170; amb lobate. Aperriires. - 3-colpomte. colpus 20.1 [im long, ca. 1.2 Iim Gruna 34 (1995)

wide, membrane granular, margo 1.O ym thick; 0s markedly laterally elongated, len 1.6 pn, width 6.9 pm, margin 1.I Iim thick. Apocolpium diameter 4.3 pm. Exiiie. - Subtectate, minutely reticuloid, brochi elongated and narrow, giving 8 striate appearance, with SEM evenly foveolate to finely fossulate. Uapaca ncirnriitata (Hutch.) Pax & K. Hoffm. Nigeria: Ikom. Cadhall 74 (Fig. 8 LQ). Size. - P: 21.3 Iim (19.5-22.5 Iim), E: 22.0 ym (21.O-23.0 pn). Exine ca. 2.3 Iim thick. Shape. - Oblate spheroidal, PIE 93-98; amb peritreme, sides straight to convex. Apertirres. - 3-colporate, very rarely 4-colporate (about 0.5% of grains studied). Colpus 14.1 pm long, ca. 1.1 ym wide, membrane minutely punctate and spinulous as seen with SEM, margo ca. 1.9 Iim thick; 0s laterally elongated, polar length 4.0 pm, width 7.0 pm. with granular membrane. Apocolpium diameter 7.0 pm. him. - Subtectate, with LM pattern seems reticulate, heterobrochate, muri supported by one to three rows of bacules, but with SEM pattern is reticulate-like, muri with supratectal spinules, lumina of varying size and shape, some with bacules. - N.B. The pollen grains of Unpncn corbisieri De Wild (Syn. U. esciilentn), U. giririeerzsis, U. paliidosa, U. stairdtii and U. togoemis described by Sowunmi (1973: 160-162) were similar to one another and to those of U. aciurtirtata. The pollen of U. grririeerrsis viewed with SEM were practically indistinguishable from those of U. acimiiiiata with regard to exine pattern. It would be desirable to examine those of the other four species of Uapaca with SEM in order to ascertain if these also have supratectal spines and bacules within lumina. Gut t i ferae Allnnblackiafloribirrida Oliv. Nigeria: Okomu F. R., Benin. Brenam 8915 (Fig. 9 A-E). Size. 1 P: 31.2 Iim (29.0-34.0 p), E 3.8 tun (31.O-37.5 pm). Exine ca. 2.0 Iim thick. Shape. - Oblate spheroidal, PE 91-94; amb rectangular, sides convex. Apertirres. - 4-colporate. Colpus 17.0 [im long, 9.0 pn wide, rounded at ends, membrane with scattered, minute verrucae in SEM, margo ca. 2.6 pn thick, granular; 0s longitudinally elongated where it coincides with colpus, but with short, very narrow, lateral extensions which taper sharply to ends, polar length and width within colpus 5.6 pm and 3.7 pn, respectively, total width 11.8 pm, margin prorninent 2.3' iim thick. Apocolpium diameter 17.3 pn. Erine. - Tectate, tectum smooth as seen in optical cross section, surface with a faint LO-pattern formed by rounded processes; SEM tectum densely fossulate except around the apertures where depressions are absent, provided with numerous, minute, supratectal verrucate processes of varying Polleri of woody Nigerinri plniifs 133 size and sparsely distributed or absent in parts at the apertural area. RIeliaceac Carapa procera DC. S.W. Cameroon. Thomas 2353 (Fig. 9 F-M). Size. - P: 28.7 [im (27.5-30.0 pm), E 28.0 Iim (27.0-29.0 pm). Exine ca. 1.6 pn thick, ca. 3.5 }im thick at apertures. Slzape. - Prolate spheroidal, P/E 102-103; amb peritreme. Apertirres. - 4-colporate, very rarely 3- or 5-colporate (0.4% or 0.8% of 260 grains viewed, respectively). Colpus comparatively short and narrow, length 13.2 pn, width ca. 0.9 pm, membrane granular, margo granular, ca. 1.0 Iim thick; 0s slightly laterally elongated, polar length 3.5 [im, width 4.5 pn, annulus granular and very prominent, 1.I Iim thick. Apocolpium diameter 155 pm. Exine. - Pattern faint in Lhl, with SEM, tectate, densely and deeply fossulate, seems punctate in parts, surface with unevenly spaced, minute verrucate processes of varying size. Khayn grnridifolioln C.DC. Nigeria: Onitsha. Roosevear 2129, (Fig. 9 N-R). Size. - P: 32.9 Iim (31.O-35.0 p), E: 30.2 Iim (28.5-35.0 Iirn). Exine 0.9 Iim thick, 3.0 pn thick at aperatures. Slzape. - Prolate spheroidal, P/E 100-109, some grains subprolate, P/E 123, amb peritreme. Aperfirres. - 4-colporate. Colpus 23.2 Iim long, ca. 3.7 pm wide, tapering to ends, membrane densely granular as seen with SEM, margo smooth to faintly granular, ca. 11.2 pm thick, 0s circular to slightly laterally elongated, polar length 3.5-4.0 Iim, width 3.5-5.0 Iim, margin ca. 0.6 Iim thick. Apocolpium diameter 12.2 pm. Exirze. - Pattern indistinct with LM, in SEM tectate and fossulate, depressions being mostly shallow, surface with densely but unevenly spaced verrucae of varying size, more prominent than in Cornpa procern. K. seriegolerisis (Desv.) A. Juss. Nigeria: Zaria. King-Church 48, (Fig. 10 A-G). Size.- P 28.0 Iim (26.0-30.0 pm) E 28.1 pm (25.0-31.0 pm). Exine 1.1 pm thick, 2,O Iim thick at apertures. Shape. - Oblate spheroidal to prolate spheroidal, PE 97-104; arnb peritreme. Apertures. - 4-colporate, may be 3-colporate (5.9% of 222 grains viewed). Colpus 17.8 pm long, ca. 3.2 pi wide, tapering sharply towards ends, membrane densely granular in SEM, margo ca. 1.O pni thick; 0s mostly circular, 3.0 pn x 3.3 ym, annulus ca. 1.0 Iim thick. Apocolpium diameter 11.8 ym. Exiite. - Tectate, details very similar to those of K. gmwdifoliola, except that in SEM surface is less markedly fossulate and undulating in latter. N.B. The pollen grains of Carapa procera. Khaja grandifolia. and K. senegcilensis are broadly similar in their important, basic morphological features, i.e. aperture details and exine pattern. Cruiin 3.1 (199.5)

Fig. I I. hlimosaceae. A-D. Fipradeniasrriiiiz africaiziiin. (C) distinct annulus (D) note operculum of 0s. hlonceae. E-I. Morris ii~esozjgin. (H) two pores, x 1000. (I) pore and minute supratecal processes, x 5000. Olacaceae. J-P. Ol~~sirDscorl,ioidea. (J) note operculum. (K) note annulus. (L) aberrant 4-porate grain. (hl) operculuni, x 3000. (N, 0) x 2000, note annulus and polar cavity with grooves radiating from it. (P) exinc pattern and convoluted structure of operculuni, x 8000. A, B, C, D, E, F, G, J, K, L - Lhl x 1000. Rliniosaceae Albizin ndinrztliifolin (Schum.) W. E Wight, Nigeria: Okomu F. R., Benin. Ebuade 9124, Fig. 10 H-P). Size. - 16-celled polyad, 75.9 Itm x 67.4 pi; single cell: P: ca. 25.3 pi, E: ca. 28.5 Itm. Exine thickness not even throughout, ca. 3.2 pm and ca. 1.I Itm at distal and proximal face, respectively. Polyads separate easily on acetolysis. Shape. - Polyad flattened, elliptical in outline; shape of single cells somewhat varied, in polar view mostly symmetrically or asymetrically tetragonal, but may be triangular, sides convex; somewhat spindle-shaped in equatorial view with SEM but spheroidal in Lhl. Apertirres. - Each cell with eight pores, but often only six to seven are well displayed. Pores seem equatorial to sub- Grono 34 (I 995)

Pollen of woody Nigerian plnnrs 135 Fig. 12. Olacaceae. A, 8. SfronrDosin grod$olin. (B) convoluted structure of exine, X 6000. Papilionaceae. C-11. Pericopsis 1n.viJ ora. (D, F) annulus and granular membrane of very large 0s. (G) x 2000. (H) coarsely granular colpus nienibrane and reticulate exine, x 8000. I-Q. Ptcrocarpts sarirolirioides. (L) aberrant 4-colporate pollen grains. (h1)x 2000. (N) x 4000. (0) distinct and smooth annulus, x 6000. (P) smooth margo and colpus membrane, x 8000. (Q) exine pattern, x 8000?. A, C, D, E, F, I, J, K, L - Lhl x 1000.

136 M. A. Soitmini equatorial, diameter 4.0 Iim, annulus distinct and granular, ca. 15 Iim thick. Exine. - Subtectate, deeply fissured in distal face as seen in optical cross section, resulting in blocks of tectal parts, supported by stout bacules which do not seem to rest on a nexine, i.e. nexine apparently missing, deeply areolate in surface view; tectum of proximal face undulating, baculate, but not distinctly fissured as in distal face, thin, smooth to finely fossulate; deep fissures distinctly visible in SEM which also shows a dense scatter of very minute supratectal processes not visible in LM; in SEM, tectum towards and around apertures not fissured into blocks, continuous or with minute, rather shallow depressions. Piptaderziasrrtrrri nfricariiirir (Ho0k.f.) Brenan, Nigeria: Lagos, n. Igbessa, Millen 190, KH (Fig. 11 A-D). Size. - P: 22.8 Iim (21524.0 p), E: 24.6 Iim (22.0-26.0 p), Exine thickness ca. 1.8 Iim, tapering sharply towards colpi. Shape. - Oblate spheroidal, P/E 92-98; amb peritreme. Apertures. - 3-colporate. Colpus elongated, length ca. 18.4 pm, ca. 2.5 Iim wide; 0s longitudinally elongated, polar length ca. 4.3 Iim, width ca. 3.3 pn, margin ca. 1.O [im thick, 0s pont-operculate as seen in polar view with LM. Apocolpium diameter ca. 18.4 p.. Exirie. - Subtectate, distincly though finely reticulate, homobrochate, muri supported by one row of bacules, stratification very distinct. hloraccae Mortis riiesozygin Stapf. Ghana: Akuse. Irvine 1682, KH (Fig. 11 E-I). Size.-P: 15.0pn(14.0-16.5 Iim),E: 16.9~im(16.0-18.0 p). Exine thickness ca. 0.6 Iim, but 1.O [im at pores. Shape. - Suboblate to oblate spheroidal, PIE 78-92; amb peritreme. Apertures. - 2-porate, pore somewhat circular, 2.6 x 2.4 pm, with a distinct, granular annulus. Exine. - Tectate, supported by sparsely spaced bacules as seen in optical cross section; SEM shows densely though unevenly distributed, minute, supratectal, baculate processes of varying size. Olacaceae OIax nrbscorpioidea Oh., Nigeria. De Wlde 3957, (Fig. 11 J-P). Size.- P: 18.4 pm (16.5-21.0 pm). E 27.9 Iim (26.0-33.0 pn). Exine thickness 1.6 Iim, tapering at pores. Sliape. - Oblate, P/E 63-61; anib goniotreme, sides convex. Apcrfiircs. - 3-porate, occasionally 4-porate (2,2% of 500 grains studied) Pore circular, diameter 4.4 pm, annulus distinct and granular, ca. 0.9 Iim thick, operculate, in SEM, operculum thick and deeply fossulate giving a convoluted, rosette-like structure not visible in LM; the apoporium of several grains, as seen in LM, seem to have a cavity that is often wide and triangular or sometimes of rather irregular shape; SEM confirmed the presence of such a wide cavity and showed three narrow grooves leading directly away from the cavity, one to each pore; cavity apparently only on one face, though there may be a central, three-armed depression abutting onto a ringlike invagination of exine on other face. Exirie. - Pattern faint and indistinct in LM; with SEM, surface undulating, tectum fossulate to punctate, with numerous, minute, verrucate processes of varying size. Stroriibosia grarid$olia Hook. f. ex Benth. Nigeria: Sapoba. Kennedy 2107. (Fig. 12 A-B). Size. - P: 16.2 Iim (15.0-17.0 pm), E: 18.3 Iim (17.5-19.0 pm). Exine ca. 0.9 pn thick. Slrope. - Suboblate to oblate spheroidal, P/E 86-89; anib goniotreme, sides straight to concave. Aperrirres. - 3-colporate. Colpus ca. 13.3 pn long, 2 5 pm wide, colpus membrane structure like rest of exine; 0s seems laterally elongated, mostly not sufficiently well-displayed. Apocolpium diameter 4.6 pm. fiirie. - Pattern faint and indistinct in LM; in SEM, tectate, surface coarsely convoluted, tectum fossulate to punctate. Papilionaceae Pericopsis lar$ora (Syn. Afrorniosia laxiflora). (Benth. ex Bak.) van Meeuwen. Nigeria. n. Mubi. Togola, Wit et al. 65085, (Fig. 12 C-H). Size. - P: 23.6 pm (22.0-26.0 pm), E 30.3 {im(28.5-32.5 pm). Exine thickness 2.0 [im. Slzape. - Suboblate, P/E 77-80; amb goniotreme, sides concave or straight, occasionally convex. Apertures. - 3-colporate. Colpus faintly delimited in LM, length ca. 19.0 kim, with ca. 4.1 pm, tapering very sharply to ends, membrane very coarsely granular as seen in SEM; 0s extremely large, laterally elongated to somewhat circular, polar length 11.9 Iim (10.5-13.5 pm), width 13.4 ym (10.0-14.5 pm), annulus very distinct and stratified as rest of exine, thickness 2.0 pm, 0s membrane granular, not very resistant to acetolysis. Apocolpium diameter 6.8 pn. Exirie. - Subtectate, minutely and finely reticulate, homobrochate, muri supported by one row of bacules. Pierocorpiis snntaliiioides L'Her. ex DC. Nigeria. Abeokuta. Ogun R. bank. Olorunfemi 40323, (Fig. 12 I-Q). Size.-P: 20.5 pn(20.0-215 Iim),E 15.5 pn(15.0-16.0 I'm. Exine ca. 1.7 pi thick. Shop. - Subprolate to prolate, P/E 125-134; amb peritreme. Apcrfirres. - 3-colporate, very rarely 4-colporate (0.2% of 500 grains studied). Colpus 16.4 pn long, ca. 1.8 Iim wide; in LM, markedly constricted in equatorial region, widening towards poles, but shows reverse shape in SEM, i.e. widest at and around equator, tapering sharply to ends, granular edge, Grnnn 3-1 (1995)

Pollen of woody Nigcririii plmits 131 Fig. 13. Rhamnaceae. A-F. Zizyphiis spiiimchri3i. (E) exine pattern, x 4000. (F) x 3000. Rubiaceae. G-hl. Gmfenin i/ipridis. (G) decussate tetrad. (H) composite micrograph, upper halfopticall cross-section, lowcr half - surface pattern. (I) decussate tetrad, note pores. (J) tetrahedral tetrad. (K) decussate tetrad, note vermcae bordering paired pores, 100. (L, hl) clusters of bacules with coalesced tops, x 5000. A. B, C, D, G, H, I, J - Lhl x 1000. 10 Grrrno 31 (1995)

Fig. 14. Rubiaceae. A-C. Gmknio sokotemis. (A) tetrahedral tetrad, x 1000. (B) spinules, x 8000. (C) surface pattern, x 5000. D-K. Moorindo Iitcklo. (F) aberrant 5-colporate grain. (G) inner 0s with distinct annulus. (H) annulus of outer 0s. (1) 0s membrane. (J) x 2000. (K) reticulate exine and densely granular colpus membrane. x 4000. D, E, F, G, H, I - Lhl x 1000. 0.6 pm thick, rest of margo smooth, colpus membrane mostly smooth, though in SEM may appear very faintly fossulate, with very sparse, minute blunt processes; 0s large, longitudinally elongated to circular, polar length 7.8 Itm (6.5-10.0 pm), width 6.6 p i (6.0-7.5 pi), outline faint in Lhl but in SEM, margin distinct and smooth. Apocolpium diameter 4.4 pi. Evirte. - Subtectate, distinctly though minutely and finely reticulate, homobrochate, muri simplicaculate. Rhamnaceae Zizyphirs spina-cliristi (L.) Desf. Nigeria: Kontagora. Dalziel 74 (Fig. 13 A-F). Size. - P: 25.0 ym (22.0-28.0 p ), E: 25.2 pm (23.0-29.0 itm). Exine ca. 1.7 Itm thick. SIinpe. - Suboblate, oblate spheroidal or prolate spheroidal, P/E 83-1 12; amb goniotreme, sides straight. Apertirres. - 3-colporate. Colpus 20.7 pm long, ca. 1.5 pm wide, tapering very sharply towards ends, membrane gran- Graira 3-1 (1995)

Pollen of woody Nigerim plrrrits 139 Fig. 15. Sapindaceae. A G. Allophjhrs nfricnrurs. (B) subequatorial view. (C, E) aberrant 4-porate grains (E) x 2000. (F) x 3000. (C) exine pattern, x 8000. Sapotaccae. H-K. Chrysophyllirrn strbriirdrrrn. (K) x 2000. Lo. hlanilknm obowrn. (N) x 5000. (Q) note exine pattern, x 6000. Ulrnaceae. P-U. Holoprelen grnndis. (S) x 1500. (T) x 2000. (U) pore and exine pattern, x 6000. A, B, C, D, H, I, J, L, hl, P, Q, R - Lhl x 1000.

140 hl. A. Sownnti ular in SEM, mago granular; 0s laterally elongated, polar length ca. 2.0 I'm, ca. 3.0 iim wide, margin granular, ca. 1.2 iim thick. Apocolpium diameter 6.2 pn. Eviric. - Subtectate, faintly reticuloid in LM, in SEM finely undulating, foveolate to fossulate, ridges supported by tiny bacules. Rubiaceae Gnrdcnin iiiiperialis K. Schum. Nigeria: Kiri-Dan River bank. Chapman 4702 (Fig. 13 G-M). Size. -Tetrahedral tetrad 49.9 x 54.8 Iim, decussate tetrad 52.1 x 54.7 Iim, single cell 34.7 x 28.2 Iim. Exine ca. 1.6 Iim thick, ca. 3.5 pn thick at pores. (All dimensions do not include verrucae). Slt~tp. - Tetrads tetrahedral or decussate, individual cells with varied shape, difficult to ascertain in equatorial view, amb seems pleurotreme, sides straight, angles rounded. Aperttires. - Individual cells 3-porate, pore somewhat rectangular in outline, ca. 5.8 Iim wide, with a distinct granular margin, ca. 4.0 Iim thick. Exirie. - Subtectate, with densely spaced supratectal verrucae of varying size, diameter ca. 2.0 Iim to 4.0 pm, some of the largest verrucae border pores; below and in between verrucae are bacules whose coalesced tops form the partial tectum; in SEM, tectum very thin and mainly discontinuous. G. sokoteitsis Hutch. Nigeria: Sokoto province. Yesufu 5206 (Fig. 14 A-C). Size. - Tetrahedral tetrads 47.5 x 53.3 tun, decussate tetrads 54.2 x 479 Iim, single cells 30.0 x 20.5 pn. Exine 1.7 pi thick, much thicker at pores. 5.0 pm. (All dimensions do not include verrucae). Shnp~. - Tetrads tetrahedral or decussate, shape of individual cells in equatorial view varied and difficult to ascertain, amb pleurotreme, sides straight, angles rounded. Apcrtiircs. - Individual cells 3-porate, outline of pore more circular than in G. iniperinlis, annulus very distinct and granular, ca. 4.6 p i thick. Evirte. - Subtectate, provided with densely spaced spinules and spines of varying size, height 1.7 p-n to 4.4 pm, basal diameter 0.8 pm to 3.8 pin, bordering pores are larger spines, height ca. 5.5 Iim, basal diameter ca. 4.2 Iim (may be up to 9.0 p), spin(ul)es stout but taper abruptly towards tips, ending in a tiny knob; in between and below spif(ul)es are very numerous bacules whose coalesced tops form a partial, discontinuos tectum as in G. i/iiperidis. hforiltd~ hicidn Benth. Zaire: Sangaie. Gillardin 447, (Fig. 14 D-K). Size. - P 41.5 Iim (39.042.5 pm), E: 46.2 Iim (44.0-48.0 Iim). Exine 3.0 Iim thick. Shnpe. - Suboblate to oblate spheroidal, PIE 83-89; amb tetragonal, pleurotreme, sides convex. Apertrires. - 4-colporate, rarely 5-colporate (1.2% of 340 grains studied). Colpus ca. 30.3 pm long, ca. 4.7 pm wide, Grciito 34 (I 999) rounded at ends, coarsely and densely granular membrane distinct in SEM but very faint in LM; 0s large, markedly laterally elongated, polar length 10.5 Iim (8.5-13.0 pm), width 21.7 pm (19.5-32.0 pm), gently tapering towards ends, membrane seems to be a practically unmodified extension of exine, 0s appears double because has an outer granular margin ca. 1.5 Iim thick, and an inner, distinctly granular one, ca. 2.5 Iim thick demarcating part of 0s which is circular to longitudinally elongated, polar length 6.6 pm (5.0-9.5 Iim), width 5.3 Iim (3.0-9.0 I'm) Apococolpium diameter ca. 16.7 pn. Evine. - Subtectate, coarsely reticulate, mursi supported by one (or two?) row(s) of bacules, some lumina have few bacules. Sapindaceae All~pli~llti~ nfricmtirs P. Beauv. Nigeria: Ibadan. Kennedy 182; P. Wit 2267 [for SEMI. (Fig. 15 A-G). Size. - P: 19.0 Iim (I 6.0-2 I.5 pm), E: 27.9 Iim (24.5-30.5 pm). Exine ca. 2.0 pi thick. Sliope. - Oblate, P/E 65-74; amb goniotreme, sides straight, sometimes partly concave or convex. Apertures. - 3-porate, rarely 4-porate (2.5% of 158 grains). Pore large, often not well displayed in equatorial view, ca. 6.5 [im, x ca. 7.5 pm, margin granular, ca. I.7 Itm thick, membrane granular. Apoporiuni diameter 21.I [im. Eviite. - Subtectate, finely striate to striato-reticulate; in SEM deeply fossulate, tectal ridges finely striate, anastomosing depressions with very narrow slits or foveolate in parts, resulting in a striato-reticuloid pattern. Sapotaceae Clirjsopltjlhiin stibiirrhaii Bak. Nigeria: Calabar. Latilo (Fig. 15 H-K). Size.-P: 23.7 pm (21.0-255 [im).e: 14.3 p(13.0-15.0 Iim). Exine ca. 15 Iim thick. Apertrrres. - 3-colporate, rarely 4-colporate (2.9% of 103 grains viewed). Colpus rather faintly delimited, ca. 19.3 Iim long, ca. 1.5 [im wide, rnargo ca. 0.8 Iim thick; in SEM membrane smooth, with few granules; 0s in Lh?, laterally elongated, polar length 2.0 Iim, width 3.7 pm, with a distinct, smooth margin ca. 1.9 prn thick, but in SEM seems longitudinally elongated with a prominent membrane which is smooth but deeply fissured and convoluted (Fig. 15 M & 0 resp.). Apocolpium diameter 6.9 pn. hfmdkorn obowto (Sabine & G. Don), J. H. Hemsley, Nigeria: n. Iseyin, Ado rock. Leeuwenberg & Latilo 66943, (Fig. 15 LO). Size. - P: 25.6 Iim (24.0-26.5 pn), E: 19.1 Iim (17.5-20.5 Iim). Exine ca. 1.7 Iini thick. Sliqie. - Subprolate to prolate, PIE 130-142; peritreme. Apertiires. - 4-colporate. Colpus rather narrow, 20.8 pn long, ca. 0.8 Iim wide, margo ca. 1.0 Iim thick, membrane

finely and sparsely granular in SEM; 0s laterally elongated, polar length 2.4 Itm, width 4.4 fun, distinct margin. ca. 1.7 Iim thick; in SEM membraneous 0s seems longitudinally elongated. Apocolpium diameter ca. 4.3 Iim. Exirw. - Pattern indistinct, tectum undulating in LM; in SEM, tectate, surface undulating, finely fossulate, depressions with isolated, short and very narrow slits or very minute perforations. - N.B. The morphology of the pollen grains in the Nigerian specimen studied here differs from that of the Cameroonian ones described by Caratini (I974 241) in two main respects - the grains of the former were found to be 4- colporate and smaller in size (P: 25.6 Itm, E: 19.1 pm) while those of the latter were 5-colporate and larger (P: 37.0 pm, E: 30.0 Itm). It would be worthwhile to investigate these divergencies. Caratini (1974; 241) referred to the tectum surface as being irregular, but the features shown in his SEM micrograph (pl. 187: 15). are similar to those of the Nigerian specimen illustrated here (Fig. 16 A). Ulmaceae Holopfelea grandis (Hutch.) Mildbr. Nigeria: Ile-Ife. Brenan 8982, (Fig. 15 P-U). Size. - P: 24.8 Iim (23.5-26.0 pm), E: 29.4 p n (27.5-3 1.5 Itm). Exine ca. 1.7 pm thick, ca. 2.1 ltm thick at the apertures. Shape. - Suboblate, PE 75-83; amb peritreme, rounded pentagonal. though asymmetrical. Apertrrres. - 3-porate. Pore longitudinally elongated, ca. 4.3 ltm x, ca. 2.7 pm, margin granular, ca. 2.1-2.9 Itm thick, membrane granular. Exine. - In LM, surface undulating, with numerous vermcate processes of varying shape and size; in SEM tectate, deeply fossulate, fossulae partition tectum into tubercle-like protuberances (the verrucate processes of LM) of varying size and shape, which are mostly interconnected by very thin exinous strands across fossulae; where there are no exinous strands, fossulae have very narrow and short slits: entire surface of grain densely studded with very minute vermcate processes not visible in LM. ACKNOWLEDGEMENTS This study was carried out during a period of paid study leave spent at the Palynology Unit of the Royal Botanic Gardens. Kew, England. I thank the University of lbadan for granting me both the leave and the travel funds. hly deep gratitude goes to the British Council whose generous financial assistance made my sojourn at Kew possible. I am greatly indebted to Dr. I. K. Fcrguson, Head of the Palynology Unit at Kew, for welcoming me to spend my study Pollen of woody Nigerian plants 141 leave at the Unit and for graciously placing at my disposal all the necessary facilities. I sincerely thank him and all other members of the Unit for making my stay at Kew very rewarding, pleasant and congenial. I am grateful to the Director of the Kew Herbarium for permission to collect pollen samples. 1 thank the staff of the Photographic Section at Kew, especially hls. Sue Ellison, for their prompt production of Lbl and SEhl micrographs. Finally, many thanks are due to hlr. R. hl. Ramoni for skilful typing of the manuscript. REFERENCES Agwu, C. 0. C. & Akanbi, T. 0. 1985. A palynological study of honey from four vegetation zone of Nigeria. - Pollen Spores 27: 335-348. Caratini, C. 1974. hfodkam obovnfa (Sabine & G. Don). In - : Pollen et Spores d Afrique Tropicale (ed. Cl. Caratini & Ph. Guinet). pp. 241, 243. - Cent. Etudes Geogr. Trop. Doniaine Univ. Bordeaux. Dimbleby. G. W. 1985, The palynology of archaeological sites. - Academic Press, London. El Ghazali, G. E. B. & Krzywinski, K. 1989. An attempt to clarify the term heterocolpate. - Grana 28: 179-186. Erdtnian, G. 1966. Pollen morphology and plant taxonomy. Angiosperms, offset edition with addendum. - Hafner Pub. Co., New York. Faegri, K. & Iversen, J. 1975. Textbook of pollen analysis, 3rd ed. by K. Faegri. - hlunksgaard, Copenhagen. Fredoux. A. 1974. Raavolfin voniiforiu (Afzel.) - In: Pollen et Spores d Afrique Tropicale (ed. Cl. Caratini & Ph. Guinet), pp. 60.64. - Cent. Etudes Geog. Trop. Domaine Univ. Bordeaux. Hutchinson. J. & Dalziel J. hi. 1954-1968. Flora of West Tropical Africa, 1-111. - Crown Agents Overseas Govts. & Admin., London. Jackson, B. D. 1928. A glossary of botanic terms with their derivation and accent. - In: hlorphologic encyclopedia of palynology (ed. G. 0. W. Kremp, 1965), p. 171. - Univ. Arizona Press, Tucson. Le Thomas, A. 1974. Asferanrlze nsferins (Moore) Engler & Diels & Hexalobus nionoperalris (A. Rich) Engler & Diels. - In: Pollen et Spores d Afrique Tropicale (ed. CI. Cantini & Ph. Guinet), pp. 53-55. - Cent. Etudes Geogr. Trop. Domaine Univ. Bordeaux. Lowe, J. & Soladoye, hl. 0. 1990. Some changes to names of Nigerian plants since the publication of the Flora of West Tropical Africa ed. 2 and Nigerian Trees. - Nig. Jour. Bot. 3: 1-24. Nilsson, S. & Robyns, A. 1986. Bombncaceae. - In: World Pollen and Spore Flora. No. 14. (ed. S. Nilsson).- Almquist & Wiksell, Stockholm. Pouniot, C. 1989. Palynological evidence for eustatic events in the tropical Neogene. - Bull. Centres Rech. Explor. Prod. Elf-Aquitaine 13: 437453. Sowunmi. hl. A. 1973. Pollen grains of Nigerian plants 1. Woody species. - Gnna 13: 145-186. Sowunmi, hl. A. 1976. The potential value of honey in palacopalynology and archaeology. - Rev. Palaeobot. Palynol. 21: 171-186. Sowunmi, hl. A. 1988. Palynology and Archaeology. - Excavator 1: 2636. Grana 31 (1995)