Pollen morphology of Adenandra (Rutaceae: Diosminae) and its taxonomic implications

The pollen morphology of Adenandra Willd. (Rutaceae: Diosminae) was investigated to determine its taxonomic significance. Pollen of 27 of the 30 infrageneric taxa (representing 16 of the 18 species) was investigated by LM, SEM and TEM. Adenandra differs from all other Diosminae in having 4-colporate rather than 3-colporate pollen grains. This supports the alleged monophyletic status of the genus. Exine morphology and structure, however, is extremely diverse considering the size of the genus, with eight distinct pollen types and four subtypes being discerned. In some members the grains have uniform macroreticulate, striate or striato-reticulate sculpturing, whereas in others the poles have striate, striato-reticulate or reticulate-perforate sculpturing with various types of reticulate or rugulate sculpturing at the mesocolpia. Taxonomic groupings revealed by the pollen characters suggest elationships between taxa that were not previously apparent. It is suggested that evolutionary diversification among species of Adenandra is often more strikingly reflected by pollen morphology than by macromorphology, hence the eurypalynous state of the genus.     

Pollen morphology of Phyllosma and Sheilanthera (Diosminae: Rutaceae) and its taxonomic implications

Phyllosma (two species) and Sheilanthera (one species) are members of the taxonomically problematic subtribe Diosminae, Rutaceae. Pollen morphology of all three species was investigated by LM, SEM and TEM to shed light on their relationships to other genera of the subtribe. Sheilanthera shares pollen morphological features with many other species in the subtribe, but the pollen of Phyllosma is distinctive. Possible relationships between Sheilanthera and Acmadenia, and between Phyllosma and Agathosma are suggested. The macromorphological characters of the species correspond to the pollen morphology.     

Palynology of Acmadenia (Diosminae: Rutaceae) and its taxonomic implications

The palynology of Acmadenia (Diosminae: Rutaceae), a taxonomically problematic genus, was investigated to determine its taxonomic significance. Pollen of 32 of the 33 species, and one undescribed species, was investigated by LM, SEM and TEM techniques. Exine structure is extremely variable in proportion to the size of the genus, with seven distinct types and four subtypes being discerned. Species groupings elucidated by the pollen types suggest relationships between species which were not previously apparent. Pollen data supports morphological evidence for the re‐classification of Acmadenia. A redefined Acmadenia is proposed to consist of 23 species, whereas the remainder of the taxa should be referred to new or closely related existing genera.     

Pollen morphology and its taxonomic significance of the monotropoideae (Ericaceae)

A palynological survey, including LM, SEM and TEM is presented for eight genera, nine species and 76 samples of the Monotropoideae which is composed of 10 genera and 13 species. On the basis of the aperture number and shape, the following six pollen types are recognized: 1) 3-colp(oroid) ate—Allotropa, 2) 2-colpor(oid)ate—Monotropsis andHemitomes, 3) 4-colpor(oid)ate—Pterospora, Sarcodes andPleuricospora, 4) 2- and 3-colpor(oid)ate—Monotropa hypopitys, 5) 3-colporate and-porate —Monotropa uniflora, 6) 3- to 4- porate—Monotropastrum humile. Relationships among taxa within the Monotropoideae are illustrated on the palynological characters including the aperture type, exine sculpture and structure. Both pollen grains with two and four apertures have evolved independently from pollen grains with three apertures, according to the infraspecific variation of aperture numbers and the usual occurrence of three-aperturate pollen grains in the Ericaceae. 3-colp(oroid)ate pollen ofAllotropa is the most primitive and occupies an isolated position in the subfamily, on the other hand 3- to 4-porate pollen ofMonotropastrum humile is most advanced in the subfamily, probably even in the Ericaceae. A reduced sexine inMonotropastrum humile appears to be a specialized pollen character. Infraspecific geographical difference in palynological characters is revealed in two species ofMonotropa for the first time.M. hypopitys is basically characterized by pollen grains with two apertures in the New World vs. three apertures in the Old World.M. uniflora is basically characterized by 3-porate pollen in the New World vs. 3-colporate in the Old World. In both species pollen grains with more primitive characters usually occur in the Old World.     

中国算盘子属(叶下珠科)果实形态特征及其分类学意义

算盘子属是一个分类较为困难的大类群,全世界超过300种,其中众多物种间的界定至今颇存争议。本研究在野外考察及对馆藏标本查阅的基础上,对中国算盘子属21种1变种的果实形态进行了仔细观察和研究。结果显示,该属物种果实被毛情况、果实大小、宿存花柱、纵沟深浅和数目等形态特征在种间具有很高的多样性,可用于对不同物种的鉴别,具有一定的分类学价值。基于果实形态特征提供了这21种1变种的分类检索表。     

Pollen morphology of Chinese Glochidion (Phyllanthaceae) and its taxonomic implications

The pollen morphology of twenty‐five Chinese species belonging to two sections of Glochidion and one species from Phyllanthus subgen. Phyllanthodendron was examined using scanning electron microscopy (SEM). The results showed that pollen grains of Glochidion are isopolar, spheroidal to rarely subprolate in shape, (3)4–5(6)‐colporate in aperture pattern, and tectate‐reticulate to tectate‐rugulate in exine ornamentation. Fusion of colpus ends was observed in some pollen grains of G. pseudo‐obscurum and G. wrightii. The pollen grains of Phyllanthus dunnianus are similar to those of Glochidion species in their spheroidal shape and four‐colporate aperture pattern, but are slightly larger in size, and show tectate‐perforate exine ornamentation. In Glochidion, pollen morphology appears to be useful for distinguishing several macromorphologically similar. Additionally, palynological characters provide evidence for the taxonomy of the supergenus Phyllanthus s.l.     

Pollen morphology of some species of Vernonia s. l. (Vernonieae,Asteraceae) from Argentina and Paraguay

Pollen morphology is widely used in taxonomic treatments of tribe Vernonieae, and differences in exine structure and aperture form have been described for many species within the genera comprising the tribe. However, in recent years a number of new species have been described and, in the present paper, we describe in detail the pollen of 24 species of the tribe which are either endemic or uncommon to certain regions of Argentina or of Paraguay. The pollen of these species are radially symmetrical and more or less spheroidal, 3‐colporate or, in one species, 3‐porate; the exine may be tectate or semitectate and microperforate, with echinate lophae or, in the 3‐porate example, psilate lophae. Using a range of characteristics related to size, shape, wall thickness, apertures and tectum surface morphology, five of the six pollen types previously described for tribe Vernonieae, and a subtype, are recognized. Our results support the usefulness of pollen morphology in helping to determine the taxonomic position of species within tribe Vernonieae.     

Pollen morphology of Euchaetis and Macrostylis (Diosminae-Rutaceae) and its taxonomic implications

Pollen morphology of Euchaetis and Macrostylis , both members of the taxonomically problematic subtribe Diosminae (Rutaceae), was investigated by LM, SEM and TEM. Here we report on the taxonomic significance of pollen morphology based on a comparative study of 28 infrageneric taxa. Three pollen types were found, namely reticulate (common to both genera), perforate (in Euchaetis ) and striato-reticulate (in Macrostylis ). Pollen data provide evidence of relationships between the two genera as well as with other genera, and further support for the macromorphological evidence suggesting the generic re-classification of the Diosminae.     

Pollen morphology of Strobilanthes Blume (Acanthaceae) in China and its taxonomic implications

The pollen morphology of 37 Chinese species of Strobilanthes Blume (Acanthaceae), a large and taxonomically problematic genus, was investigated by LM and SEM. Two distinct pollen shape classes, ellipsoid and spheroidal, recognised by earlier workers were found. Eight pollen types could be distinguished on the basis of variation in ornamentation, and the number, distribution and type of apertures. Five of these fall within twenty two pollen types reported from Strobilanthes in southern India and Sri Lanka. Three new pollen types are also described, further extending the palynological diversity of the genus. From the results presented, the characters of palynological diversity and the related taxonomic implications are discussed.     

Pollen morphology in Primula sect. Carolinella (Primulaceae) and its taxonomic implications

Pollen morphology in Primula section Carolinella has been investigated for the first time. Seven of the nine species constituting the section were available for study, i. e., P. cardioeides, P. chapaensis, P. intanoensis, P. kwangtungensis, P. kweichouensis, P. partschiana , and P. rugosa, A considerable variation in pollen morphology was found among the investigated species, particularly in number and arrangement of the apertures. Pollen of different species were either tricolpate, tricolporate, trisyncolpate, or polycolpate. Within Primula , the section Carolinella is diagnosed by having calyptrate capsules and leaves with revolute vernation, but the variation in pollen morphology indicates that this group is heterogeneous, and that either polycolpate pollen or a capsular lid has evolved more than once in the genus Primula.     

Pollen morphology of the genus <Emphasis Type="Italic">Skimmia</Emphasis> (Rutaceae) and its taxonomic implications

Pollen morphology of the genus Skimmia was studied. Of six species of the genus, five species were investigated by light microscopy and scanning electron microscopy. Pollen grains of Skimmia had striate to striate-reticulate sculpture and variable aperture number (3-7), and these characters differed from even the phylogenetically closest relatives such as Dictamnus and Casimiroa which have 3-colporate pollen grains with reticulate exine. In Skimmia laureola, pollen dimorphism is suggested in the aperture number in accordance with the floral system. Pollen grains of Skimmia japonica, a morphologically very variable species, were extensively surveyed covering its whole distribution area. The grains were also striate to striate-reticulate, and the exine sculpture was not different between varieties. However, the aperture number of S. japonica showed a geographical variation ranging from 4 to 6; in Sakhalin, Hokkaido, most part of Honshu and Taiwan, grains with 4-5 apertures were dominant, while in the southern part of Japan, including the Ryukyu Islands and the Izu Islands, those with 5-6 apertures were common.     

Pollen morphology of the subfamily Aurantioideae (Rutaceae)

The Aurantioideae is one of seven subfamilies of the Rutaceae consisting of two tribes, the Clauseneae, containing five genera, and the Citreae, with 28 genera. Each tribe contains three subtribes. The pollen morphology of the subfamily Aurantioideae is described and illustrated for the first time based on light and scanning electron microscopy. Five pollen types have been recognised in the subfamily, based mainly on aperture number and exine ornamentation. The pollen grains show a high degree of intergeneric variation. Pollen grains of Clauseneae are 3-colporate, microstriate or microstriato-reticulate, whereas pollen grains of Citreae are almost always 4/5 colporate with exines varying from microperforate to coarsely reticulate. Congruence between pollen types and the currently accepted classification is discussed, as well as the systematic implications of pollen morphology for the subfamily.     

Pollen morphology of the subtribe Cuspariinae (Rutaceae)

The neotropical subtribe Cuspariinae (Rutaceae) comprises as many as 26 genera and over 125 species. Pollen grains from 111 collections representing 71 species and 24 genera were examined by LM, SEM, and TEM. The pollen morphology of this subtribe is very diverse. Grains are mostly 3–6-aperturate and colporate, rarely porate (Spiranthera) or pantocolporate (Almeidea). Exine sculpturing is most commonly reticulate, sometimes perforate, foveolate-perforate, foveolate, foveolate-reticulate, reticulate, striate-reticulate, echinate, clavate, or baculate. The exine structure is columellate and tectate-perforate, columellate and semitectate, or intectate and is stratified into ektexine and endexine. The exine ofLeptothyrsa is distinctive in that the ektexine of the mesocolpium is longitudinally deeply ridged. The pollen ofHortia, characterized by a psilate exine with rare perforations, a very thick foot-layer, and reduced columellae, is unlike that of any member of the Cuspariinae and offers no support for the transfer of this genus from the Toddalioideae. The pollen data correlate with macromorphological characters and are taxonomically useful.     

Pollen morphology ofPyrola and its taxonomic significance

Pollen from 152 collections representing 16Pyrola species was examined with LM, SEM and TEM. The genusPyrola is stenopalynous in having tetrads and 3-colporoidate grains. However, a continuous and serial variation in the exine sculpture and the tetrad diameter (D) was revealed within the genus. Křísa's system ofPyrola (1971) was re-examined in the light of these palynological characters which may have a taxonomic significance, as well as the external morphology. P. minor (only member of the subgenusAmelia), which is characterized by having small (D=30–35 μm) pollen tetrads with verrucate sculpture must best be placed near sectionPyrola of the subgenusPyrola. P. faurieana must be segregated from sectionChlorantha and together withP. media placed intermediate between the subgenusAmelia and sectionPyrola of the subgenusPyrola based on their larger (D=ca. 40 μm) pollen tetrads with verrucate sculpture. Two series of sectionChlorantha excludingP. faurieana are differentiated in the exine sculpture. Therefore, they are regarded as the distinct taxonomic groups. SectionScotophylla is characterized by having psilate sculptured pollen tetrads, which indicates that its sectional rank is sufficiently asserted. The evolutionary trend in the exine sculpture from verrucate through rugulate to psilate is suggested withinPyrola.     

Pollen morphology supports the reinstatement of Bergera (Rutaceae)

Pollen morphology of 11 species of Murraya and Micromelum (Clauseneae: Rutaceae) was investigated using scanning electron microscopy (SEM) and palynological characters including pollen size, aperture number and exine ornamentation were evaluated. The results indicate that species in M. sect. Bergera and sect. Murraya have very distinct pollen morphology. Species in section Bergera have rugulate to foveolate exine, whereas the tectum in section Murraya is cross-striate. This supports the redefinition of the genus Murraya , retaining only the species of section Murraya , while M. sect. Bergera is better treated as a separate genus. From the palynological point of view, it is suggested that Bergera and Murraya s.s. are not closely related, with the latter being more close to Micromelum and Merrillia , a result in accordance with phytochemical, chromosomal and molecular evidence, thus supporting the reinstatement of the generic name Bergera L.     

Pollen morphology and taxonomic implications of Muscari Miller (Hyacinthaceae) species from Sicily

Pollen morphology of the native Sicilian species of the genus Muscari, one of which is endemic to Sicily, belonging to the subgenera Muscari, Leopoldia and Pseudomuscari, was studied using a light microscope and a scanning electron microscope. Pollen grains are monads, heteropolar and monosulcate; the exine is semitectate reticulate and perforate. The sulcus extends from distal to proximal face and its length is not directly proportional to the size of the granules and varies from one species to another.     

Pollen diversity in the genus Ptilostemon (Asteraceae,Cardueae) from Italy and its taxonomic and palynoecological implications

The results of a study on pollen morphology of the species of the genus Ptilostemon growing in Italy: Ptilostemon niveus, P. greuteri, P. gnaphaloides, P. casabonae, P. strictus, P. stellatus by light and scanning electron microscopy were presented and discussed including in relation to their taxonomic position. The exine shows two different ornamentation patterns: echinae and scabrae. This last ornamentation pattern together with other features was previously described in the genus Ptilostemon. Of 6 species analysed, P. stellatus is the only one that shows a scabrate ornamentation of exine. Two pollen types were recognized through the exine ornamentation, length of ectocolpus and polar outline: P. stellatus type and P. niveus type. A multivariate analysis (principal component analysis and linear discriminant analysis) was carried out with the aim of examining potential morphological characters which could be used to identify taxa. The data suggest that several characteristics can be used to delimit the species in particular the exine ornamentation. The results of our studies support the actually subgeneric classification, and several features of the pollen grains analysed seem to have a palynoecological role and an important taxonomic significance. A dichotomous key based on palynological data is also given.