Nephelieae pollen (Sapindaceae): Form, function, and evolution

Two main types may be distinguished within Alectryon pollen: the colporate type and the parasyncolporate type. These types are not clear-cut, but merge into each other through a complete series of intermediate forms. The colporate type has usually a colporate apertural system, a high P/E value (av. 0.97), a low A/E value (0.32), and striate to striate-rugulate ornamentation. The parasyncolporate type shows usually a parasyncolporate apertural system, a low P/E value (av. 0.76), a high A/E value (av. 0.46), and striate-rugulate to rugulate ornamentation. In addition, there is some difference in endoaperture and nexine morphology, and the relative length of the peripheral columellae of a mesocolpium. An endoaperture in a colporate grain often shows acute or acuminate lateral sides or a fastigium; these characters were never observed in parasyncolporate grains. Colporate pollen has usually a less regular endexine/foot layer boundary than parasyncolporate pollen. Colporate pollen may have relatively short columellae or no distinguishable columellae at all along the colpi, whereas in parasyncolporate pollen the peripheral columellae are always relatively long

Myriophyllum aquaticum (Veil.) Verdc. verwilderd gevonden bij Moordrecht

Myriophyllum aquaticum, an aquatic plant from tropical and subtropical South America, has been found abundantly in a small ditch near Moordrecht (prov. Zuid-Holland). Plants escaped from a nursery in 1982 and survived the mild winter 1982-’83, grew luxuriously during the hot summer of 1983

Review

The aim of this book is stated as “to introduce the minute and mysterious world of pollen to as many readers as possible” and “to re-establish the morphological study of pollen taking into account newly accumulated phylogenetic information”. It provides introductory accounts on ontogeny, pollen morphology, pollination, pollen physiology, genetics of pollen, airborne pollen and pollinosis, and pollen analysis. Technically speaking it is a well-produced book, being bound in hard covers and neatly printed on good paper. Moreover, it is overwhelmingly illustrated. However, when looking and reading carefully through the book one gets a bit disappointed. Let us first consider the illustrations, which take up at least three quarters of the book. In general, the line drawings are clear and instructive. I doubt however, whether in fig. 1.7 (microsporogenesis) the vegetative and generative nuclei are correctly indicated. As to the photographs, one can not deny them being attractive at first sight. 92 full-page S(canning) E(lectron) M(icroscope) plates with micrographs of pollen grains, mainly from Japanese plants, form a kind of apocalyps at the end of the chapter on pollen morphology. Still, apart from revealing that “minute and mysterious world of pollen”, they are not functional, as in the text reference is made to only one of the approximately 175 micrographs. In all other cases the reader must guess at “the beautiful art work of nature”. Many of the micrographs have too high contrasts or show excessively magnified details (often a view of the whole pollen grain is lacking). And what about the plate on p. 60? The two polyads shown are actually identical, which is obscured however, by presenting one of them in a smaller size, turning it upside down, and cutting off some of the grains

Pollen of Southeast Asian Alchornea (Euphorbiaceae), with an overview of the pollen fossil record

In order to evaluate pollen morphological descriptions of Alchornea in the literature, which are almost completely based on African and American species, the pollen of eight Southeast Asian species of Alchornea was investigated, using light and scanning electron microscopy. Very little variation appeared to be present in the Asian material. Slightly deviating from the scabrate ornamentation type are A. kelungensis (psilate) and A. rugosa (striate-rugulate). The scabrate type is also found in A. castaneaefolia (Brazil), A. hirtella (Liberia) and A. obovata (Colombia). The operculate Alchornea pollen type, which can be easily recognised using light microscopy, seems to represent a diagnostic character for the tribe Alchornieae (pollen of Bossera unknown). Its characteristic appearance resulted in a relatively extensive fossil record. The earliest records are from the Middle Eocene of Venezuela and Nigeria, while records for Australia and Borneo date from the mid-Tertiary and the Neogene (Miocene–Pliocene), respectively. These records suggest that the tribe Alchornieae has an African– American Gondwanic origin, and reached its pantropic distribution at least in the mid-Tertiary

Integrative systematics supports the establishment of Winitia, a new genus of Annonaceae (Malmeoideae, Miliuseae) allied to Stelechocarpus and Sageraea

The generic circumscriptions of Stelechocarpus and Sageraea (Annonaceae) are assessed using molecular phylogenetic, macromorphological, and pollen morphological evidence. For molecular phylogenetic analysis the combined seven plastid markers: rbcL exon, trnL intron, trnL-F spacer, matK exon, ndhF exon, psbA-trnH spacer, and ycf1 exon constituting c. 7 kb are used. The results corroborate the recognition of a maximally supported clade as a new genus, Winitia. It is weakly to moderately supported as sister to Stelechocarpus burahol, the type and only species of Stelechocarpus. A clade consisting of Winitia and Stelechocarpus is strongly supported as sister to Sageraea, which is monophyletic with strong support. Winitia consists of two species, one of which (W. expansa) is proposed as a new species endemic to Thailand, whereas one new combination (W. cauliflora) is made. The new genus is primarily characterized by (1) multicolumellar stigmas (= 5 columns per stigma) and (2) pollen grains with a very thin tectum, a more or less columellate/coarsely granular infratectum, and a very distinct basal layer. The macromorphology and pollen morphology of the three genera (Stelechocarpus, Winitia, and Sageraea) are highlighted

Khmeriosicyos, a new monotypic genus of Cucurbitaceae from Cambodia

A new monotypic genus from Cambodia is described. The genus is defined by a unique combination of characters and has distinct pollen features. The only species is Khmeriosicyos harmandii W.J. de Wilde & Duyfjes

Integrative systematics supports the establishment of Winitia, a new genus of Annonaceae (Malmeoideae, Miliuseae) allied to Stelechocarpus and Sageraea

The generic circumscriptions of Stelechocarpus and Sageraea (Annonaceae) are assessed using molecular phylogenetic, macromorphological, and pollen morphological evidence. For molecular phylogenetic analysis the combined seven plastid markers: rbcL exon, trnL intron, trnL-F spacer, matK exon, ndhF exon, psbA-trnH spacer, and ycf1 exon constituting c. 7 kb are used. The results corroborate the recognition of a maximally supported clade as a new genus, Winitia. It is weakly to moderately supported as sister to Stelechocarpus burahol, the type and only species of Stelechocarpus. A clade consisting of Winitia and Stelechocarpus is strongly supported as sister to Sageraea, which is monophyletic with strong support. Winitia consists of two species, one of which (W. expansa) is proposed as a new species endemic to Thailand, whereas one new combination (W. cauliflora) is made. The new genus is primarily characterized by (1) multicolumellar stigmas (= 5 columns per stigma) and (2) pollen grains with a very thin tectum, a more or less columellate/coarsely granular infratectum, and a very distinct basal layer. The macromorphology and pollen morphology of the three genera (Stelechocarpus, Winitia, and Sageraea) are highlighted

Pollen morphology of genus Rubus L. Part III. Studies on the Malesian species of subgenera Chamaebatus L. and Idaeobatus L.

The results of pollen morphology of Malesian Rubus species are presented. The pollen samples represented 2 subgenera; 2 species of subgenus Chamaebatus (R. calycinus, R. pectinellus) and 13 species of subgenus Idaeobatus (R. acuminatissimus, R. alpestris, R. archboldianus, R. chrysogaeus, R. copelandii, R. ellipticus, R. ferdinandi-muelleri, R. fraxinifolius, R. niveus, R. lorentzianus, R. macgregorii, R. montis-wilhelmi, R. papuanus). The examination of these species has been made by SEM for the first time and also by LM. Detailed descriptions of the pollen grains are given. As in the majority of Rubus species, pollen grains of both subgenera are isopolar and trizonocolporate. The pollen grains were small for some species of the subgenus Idaeobatus only, medium for both subgenera: Chamaebatus and Idaeobatus. The thickest exine was observed among the species of subgenus Chamaebatus and in R. macgregorii of subgenus Idaeobatus. The ornamentation of the studied pollen has shown a great variability. Except for the typical striate ornamentation of the genus, rugulate (R. archboldianus), striatescabrate (R. lorentzianus) and striate-rugulate (R. macgregorii) ornamentation has been observed. New Guinean morphologically similar pinnate Rubus ferdinandi-muelleri, R. montis-wilhelmi, R. papuanus, have pollen with specific type of striate pattern, which is characterised by relatively high muri with variable thickness and lumina filled with granules. Some of their muri resemble baculae typical only for R. chamaemorus. The pollen morphology analysis leads to the conclusion that Rubus montis-wilhelmi and R. papuanus of subgenus Idaeobatus are the closest related species and morphologically very close to R. ferdinandi-muelleri. Since Focke placed the latter species in section Pungentes of the subgenus Idaeobatus, and the two first species were unknown to him - the authors suggest to include them into this section. Despite of the different origin and various types of leaves R. chrysogaeus, R. acuminatissimus and R. niveus have shown similarities in pollen morphology and are grouped together. On the basis of the same criteria, R. copelandii, R. ellipticus and R. fraxinifolius could have been grouped together, as well as R. alpestris and R. macgregorii. Trifoliolate R. archboldianus and R. lorentzianus have not shown similarities of pollen ornamentation to each other and to the previous mentioned species