Pollen morphology of the genus Hydnocarpus (Flacourtiaceae) with notes on related genera J. Schaeffer Rijksherbarium, Leiden Contents Summary 65 I Introduction 65 II General morphology 66 III Systematic descriptions 66 IV Pollen types 76 Pollen and V morphology taxonomy 77 References 79 Summary Pollen of ofthe described. Two grains 34 species genus Hydnocarpus(Flacourtiaceae) are pollen types, one of which is subdivided in two subtypes, are distinguished. Within Flacourtiaceae the pollen of Hydnocarpus In is more or less isolated, but the related genus Chlorocarpa has rather similar pollen. sculpture there exists some resemblance to Paropsia (Passifloraceae). I. Introduction The present study forms part of a general pollenmorphological survey of the family Flacourtiaceae, initiated at the Rijksherbarium in collaboration with Dr. H. Sleumer. The selected for the first detailed because genus Hydnocarpus was study it proved to have rather characteristic pollen types and is concentrated in SE. Asia and the Malesian region. Moreover, an adequate amountof well-determinedmaterial as well as a recent revision ot In the genus (Sleumer, 1954) were available. total 34 species could be investigated, of the total numberof known. representing 85 % species In addition, the pollen of a large other number of Flacourtiaceae was cursorily examined, in order to asses the pollen of within the morphological relationships Hydnocarpus family. The pollen of the genera and which resemble that of described Neoptychocarpus Chlorocarpa, Hydnocarpus most, is in more detail. Erdtman described Previously, only (1952) has, very briefly, the pollen of Hydnocarpus rather the elmeri which, however, proved to be atypical of genus. The pollen material was acetolysed for two minutes, mounted in glycerin jelly and photographed with a Leitz apochromatic OI objective (90/1.40). Acetolysed grains, covered with a thin layer of gold, were photographed under a Cambridge All Scanning Electron Microscope at the Geological Institute, University of Leiden. Unless indicated otherwise, all material examined originated from the Rijksherbarium (L). 65 No. 66 BLUMEA VOL. XX, I, 1972 Mr. I sincere This study was performed under supervision of J. Muller. express my thanks to Dr. H. Sleumer for providing the material on which this study is based, for discussions and taxonomic corrections, and to Mr. Muller for critically examining the Finally, take this to gratitude to Professor C. G. G. manuscript. I opportunity convey my who has been teacher and under whose J. van Steenis, my in plant taxonomy guidance of in the I have had the privilege working Rijksherbarium for two and a half years. II. GENERAL MORPHOLOGY The size pollen grains in Hydnocarpus are single, isopolar and tricolporate. Average between and Shape, defined by the ratio of length polar axis (P) to varies 17 43 [i. as length equatorial axis (E), is generally spherical but may vary between suboblate, sub- prolate and, rarely, prolate. The equatorial outline is always circular. whenever from well Size measurements were taken, possible, ten developed grains and minimum, average, and maximumsizes are given separately for P and E. Under the endexine and while the latter lightmicroscope an an ektexine can be recognized, is further differentiated into a layer of columellae and a reticulate tectum. The inner surface of the endexine be smooth. The columellae two different appears to occur in types, less in in a) supporting columellae which are more or distinctly arranged single rows a reticulate and which the of the reticulum with their somewhat pattern support muri swollen heads, and b) free columellae, which are shorter, with roundedtops, more variable in lumina of The in diameter and occurring scattered the some species. presence or absence of these free columellae forms an important criteriumfor the definition ofpollen for types in Hydnocarpus. Size and distribution pattern of the lumina are also important the others this purpose. Some species are characterized by a finer reticulum on poles, by a more even size distribution of the lumina or by finer lumina near the ektoapertures. There is also a rather marked differencebetween grains with a finely reticulate and those transitions muri biconvex in with a coarsely reticulate tectum, although occur. The are cross-section, exceptionally conical. The pollen grains are invariably tricolporate. The apertures in the ektexine (ektoapertures) are meridionally elongated slits (colpi); their relative length is indicated by the polar index (PI = width polar field/E) which varies between and with short the width 0.23 (long colpi) 0.75 (short colpi). In grains colpi, of difficult in the is the polar field may be to measure and such cases length of the colpi also indicated. The short colpi in coarsely reticulate grains may be rather inconspicuous. The endexinous wide apertures are generally oval-subrectangular, as as, or slightly sides. wider than colpi and sometimes indistinctly costate on polar III. SYSTEMATIC DESCRIPTIONS A. HYDNOCARPUS GAERTN. Section Taraktogenos (Hassk.) Warb. annamensis — I: Hydnocarpus (Gagnep.) Lescot & Sleum. Pl. 1—5. Material studied. Indo-China: Balansa 2400. Pollen grains suboblate to subprolate, P/E 0.83 (0.96) 1.20, equatorial outline circular, Size: P E Ektoapertures 1 wide at tricolporate. 27 (28.7) 30//, 24 (29.8) 35 fx. fx equator, sides parallel, tips pointed, PI 0.25 (0.33) 0.42. Endoapertures distinct, oval, 7 p. long, Total wall thickness Endexine 5 [x wide, equatorially elongated. 3 fx throughout. 1 fx thick. columellae rather Supporting reticulately arranged, 0.5 fx in diameter, variable, J. Schaeffer: Pollen morphology of Hydnocarpus 67 circular to oval in free columellae size cross-section, I fx high; o—3 per lumen, variable, to high. Tectum coarsely to finely reticulate, lumina isodiametric to slightly up 0.5 fx finer elongated, 2—3 fx in diameter, on poles, muri straight to curved, 0.5 fx wide, I /x high. Hydnocarpus calophylla (Ridl.) Sleum. — Pl. I: 6—9; Pl. VI: I—2. Material studied. Borneo: Jacobs 5181. Pollen grains spherical, P/E 0.89 (0.93) 0.97, equatorial outline circular, tricolporate. wide at sides Size: P 33 (35.9) 39 fx, E 35 (38.6) 41 fx. Ektoapertures 3.5—5 fx equator, parallel at equator, tapering to pointed tips, PI 0.42 (0.47) 0.51. Endoapertures distinct, direction. Total wall rectangular-oval, 18 fx long, 7 fx wide, elongated in equatorial thickness Endexine thick. columellae 4.5 /X throughout. 2—4 /x Supporting reticulately arranged, —2 in diameter, rather variable, subangular-circular to -oval in 1.5 fx cross- free columellae to section, 1.5 [X high; 2—8 per lumen, size variable, up 0.5 fx high. Tectum coarsely reticulate, lumina irregularly shaped, isodiametric to slightly elongated, 2 in diameter, uniformly distributed, muri straight to curved, I wide, 1 high. —5 fi fx fx Hydnocarpus hainanensis (Merr.) Sleum. Material studied. Hainan: F. C. How 70706. Pollen grains spherical, P/E 0.89 (0.94) 1.04, equatorial outline circular, tricolporate. Size: P E 1 wide at sides 23 (25) 27 /x, 25 (26.5) 28/x. Ektoapertures fi equator, parallel, pointed, PI (0.28) Endoapertures indistinct, oval to rectangular, 6 tips 0.19 0.31. ± fx direction. Total wall thickness long, ± 1.5 fx wide, elongated in equatorial 2.5—3 fx throughout. Endexine 1 thick. columellae reticulately arranged, fx Supporting 0.5 fi in diameter, rather variable, subangular-circular to -oval in cross-section, —I high; 0.5 fx free columellae o—2 size to rather per lumen, variable, up 0.5 fx high. Tectum finely reticulate, lumina irregularly shaped, isodiametric to slightly elongated, I in diam- —3 fi muri to wide. eter, uniformly distributed, straight curved, I fx high, ± 0.5 fx Bl. — Pl. Pl. Hydnocarpus heterophylla I: 10—13; VI: 3—4. PNH Material studied. BS — Unesco Philippines: 41600, 23029 (ssp. philippinensis Sleum.). Java: 43, Kostermans c.s. 400 (ssp. heterophy lla). Pollen suboblate grains to subprolate, P/E 0.78 (0.97) 1.23, equatorial outline circular, Size: 22 1 wide at tricolporate. P 21 (28.5) 38 fx, E (29.6) 38 fx. Ektoapertures —1.5 fx sides indistinct equator, parallel, tips pointed, PI 0.20 (0.28) 0.40. Endoapertures to rather wide. Total wall thickness distinct, oval, ± <5—10 fx long, ± 3—7 fx 2.5—3 fx throughout. Endexine I thick. columellae in diam- ± fx Supporting reticulately arranged, 0.5—1.5 /x rather -oval eter, variable, subangular-circular to in cross-section, 1—1.5 fi high; free columellae 0 variable, to to —5 per lumen, size up 0.5 fi high. Tectum finely coarsely reticulate, lumina irregularly shaped, isodiametric to slightly elongated, in diam- 1—4 fx eter, uniformly distributed, muri straight to curved, 0.5—I fx wide, 0.5—1 [X high. ilicifolia — Hydnocarpus King. Pl. II: 1—8. Material studied. Laos: Kerr 21293. Pollen outline grains spherical, P/E 0.93 (1.00) 1.10, equatorial circular, tricolporate. BLUMEA 68 VOL. XX, No. i, 1972 Size: P E 1—2 wide at sides 27 (30.1) 33 fi, 29 (30) 31 fi. Ektoapertures fi equator, parallel, pointed, PI 0.21 (0.27) Endoapertures indistinct, oval, long, wide. tips 0.33. ±7 fi ± 3 fi Total wall thickness Endexine thick. columellae 3.5 fi throughout. 1.5 fi Supporting reticulately in diameter, rather variable, subangular-circular to -oval in arranged, 0.5 fi free columellae to cross-section, 1 fi high; 0—2 per lumen, size variable, up 0.5 fi high. Tectum coarsely reticulate, luminairregularly shaped, isodiametric to slightly elongated, variable in shape, in finer on poles, muri straight to curved, 1 1.5—2.5 /i diameter, fi wide, 1 fi high. Hydnocarpus kunstleri (King) Warb. Material studied. Borneo: — Sumatra: Forbes Jacobs 5246. 3033. Pollen grains spherical, P/E 0.85 (0.99) 1.08, equatorial outline circular, tricolporate.