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 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 supports the transfer of Wendlandia (Rubiaceae) out of Rondeletieae

Pollen morphology of 27 species, eight subspecies and one variety of Wendlandia was studied using scanning electron microscopy (SEM). Wendlandia pollen are monads, radiosymmetric, small in size, tricolporate (rarely tetracolporate or bicolporate) and spheroidal (rarely subprolate or suboblate) in equatorial view. The compound aperture consists of ectocolpus, mesoporus and endocolpus. In addition, reticulate sexine and granular nexine were observed. The pollen wall ultrastructure of two Wendlandia spp. was examined by transmission electron microscopy (TEM). The exine consists of the tectum, columellae, foot layer and endexine. The endexine is thickened into a costa around the aperture. The intine forms a protruding oncus at the aperture. The palynological characters show a remarkable uniformity among the Wendlandia spp. Differences with Rondeletia, the main genus of tribe Rondeletieae, exist in the exine pattern, the endoaperture and the pollen wall structure. Our observations indicated that the endoaperture type and the structure of the pollen wall of Wendlandia were similar to those of the Gardenieae–Pavetteae–Coffeeae–Octotropideae clade, which provided palynological evidence for a closer relationship of Wendlandia to subfamily Ixoroideae and the transfer of Wendlandia out of Rondeletieae. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 128–141.     

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.     

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

The pollen morphology of Diosma and Coleonema of the taxonomically problematic subtribe Diosminae (Rutaceae) was investigated to determine its taxonomic relevance. Pollen of 26 of the 28 species of Diosma and of each of the eight species of Coleonema was investigated by LM, SEM and TEM. In pollen of Diosma the exine sculpturing is uniform, and only one pollen type, reticulate, could be distinguished. In contrast, exine sculpturing shows interspecific variation in Coleonema and three distinct types, striate, reticulate and perforate, could be discerned. Species groupings indicated by the pollen types suggest possible relationships between species within Coleonema and with other genera that were not previously apparent. Pollen data support macromorphological evidence that suggests the generic re-classification of the Diosminae.     

Pollen grain morphology supports the taxonomical discrimination of Mediterranean oaks (Quercus,Fagaceae)

The exine architecture and some quantitative parameters (polar and equatorial axes and their ratio) of pollen grains allow a clear discrimination between groups of Mediterranean oak species. For the differentiation of species within groups only the quoted parameters prove useful.     

山小橘属 (芸香科) 花粉形态及其系统学意义

利用扫描电镜（SEM）对芸香科山小橘属（Glycosmis）12个分类群16个样品的花粉形态特征（包括花粉大小、萌发孔及外壁纹饰等）进行了观察研究,其中光叶山小橘（G.craibii var. glabra）、长果山小橘（G.erythrocarpa）、锈毛山小橘（G.esquirolii）、长叶山小橘（G.longifolia）、亮叶山小橘（G.lucida）、海南山小橘（G.montana）、少花山小橘（G.oligantha）、小花山小橘（G.parviflora）和华山小橘（G.pseudoracemos）等9个分类群的花粉形态为首次报道。结果表明,国产山小橘属植物的花粉均为单粒花粉,近球形或长球形,花粉大小范围为(15.90~23.92)×(14.56~22.00)μm,极面观为圆形、三裂圆形或近三角形,极轴与赤道轴比值（P/E）范围为1.03~1.31,均为3孔沟;根据花粉外壁纹饰可以将国产种类划分为条网状、复条网状、条纹-穿孔纹饰以及孔穴状纹饰等四种类型,其中小花山小橘不同来源花粉的外壁纹饰差异较大,至少存在5种类型：(1) 极面穴状,赤面条网状或穿孔,(2) 极面穴状,赤面均匀分布圆形穿孔,(3) 具复条网状,(4) 条网状兼具不规则小穿孔,(5) 条网状兼近圆形穿孔纹饰。研究发现山小橘属植物的花粉形态特征具有较高的多样性,为该属植物的分类及系统学研究提供了可用的孢粉学资料。     

山小橘属(芸香科)花粉形态及其系统学意义

利用扫描电镜(SEM)对芸香科山小橘属(Glycosmis)12个分类群16个样品的花粉形态特征(包括花粉大小、萌发孔及外壁纹饰等)进行了观察研究,其中光叶山小橘(G.craibii var.glabra)、长果山小橘(G.erythrocarpa)、锈毛山小橘(G.esquirolii)、长叶山小橘(G.longifolia)、亮叶山小橘(G.lucida)、海南山小橘(G.montana)、少花山小橘(G.oligantha)、小花山小橘(G.parviflora)和华山小橘(G.pseudoracemos)等9个分类群的花粉形态为首次报道.结果表明,国产山小橘属植物的花粉均为单粒花粉,近球形或长球形,花粉大小范围为(15.90～23.92)×(14.56 ～ 22.00) μm,极面观为圆形、三裂圆形或近三角形,极轴与赤道轴比值(P/E)范围为1.03 ～1.31,均为3孔沟;根据花粉外壁纹饰可以将国产种类划分为条网状、复条网状、条纹-穿孔纹饰以及孔穴状纹饰等四种类型,其中小花山小橘不同来源花粉的外壁纹饰差异较大,至少存在5种类型:(1)极面穴状,赤面条网状或穿孔,(2)极面穴状,赤面均匀分布圆形穿孔,(3)具复条网状,(4)条网状兼具不规则小穿孔,(5)条网状兼近圆形穿孔纹饰.研究发现山小橘属植物的花粉形态特征具有较高的多样性,为该属植物的分类及系统学研究提供了可用的孢粉学资料.     

Pollen morphology of the Chloridoideae (Gramineae)

Pollen grains of 57 species (representing 42 genera) of the Chloridoideae have been investigated using light, scanning and transmission electron microscopy. Two aperture patterns and nine exine patterns are distinguished using SEM and TEM. These are categorized into five pollen types. Two pollen types are previously not recorded in Gramineae. A key for the identification of these pollen types is presented. Generally, pollen characters have limited systematic value in recognizing taxa at generic level or above in the Chloridoideae. An evolutionary trend is proposed that awaits verification by further systematic study. Pollen characters can be used as indicators for the areas of origin and distribution of the Chloridoideae.     

Pollen morphology of the Gardenieae-Gardeniinae (Rubiaceae)

Pollen grains of 107 species of 61 genera of the Gardeniinae were investigated by scanning electron and light microscopy. The subtribe is europalynous and grains occur either as monads, tetrads or massulae. Grains are porate, colporate or rarely pororate. The majority of the genera has 3-zonoaperturate pollen grains. However, deviating numbers of apertures occur in Byrsophyllum (4–8) and Pseudomantalania (4–5). Pantoporate pollen occurs in Randia . The average equatorial size (E) of monads varies between 13 μm in Anomanthodiu to 59 μm in Posoqueria . The tetrads vary from 37 μm in Casasia to 61 μm in Calochone and Euclinia . The exine is usually reticulate, but also foveolate, rugulate, perforate and psilate exine occurs in the subtribe. The thickness of the exine is only 0.3 μm in tetrad grains of Randia armata and in the pantoporate monad grains of R. ruiziana , whereas the thickest exine occurs in Posoqueria (2.8 pm) and Euclinia (2.9 μm). Tectal excrescenses are generally absent. However, three genera with pollen in tetrads, namely Euclinia, Gardenia and Oligoco-don , show this feature. Contrary to the subtribe most genera are fairly stenopalynous, but in the neotropical genera Alibertia and Randia several different types of pollen are encountered.     

Pollen morphology of Alstonia (Apocynaceae)

The pollen of Alstonia has been studied by light and scanning electron microscopy. The pollen grains are always colporate. Four distinct pollen types could be recognized. Type 1 (2‐aperturate) and type 2 (3‐aperturate) have rounded endopores, while type 3 (?<36 μm) and type 4 (?>49 μm) possess H‐endoapertures. Probably, all four types have harmomegathically inactive apertures and folding mesocolpia. Type 1 is found in five species of section Alstonia. The other species of this section and the monotypic section Winchia have type 2. The sections Dissuraspermum, Monuraspermum and Tonduzia have pollen type 3. This type may be subdivided on the basis of some minor (overlapping) features, which more or less segregate Dissuraspermum from Monuraspermum. Palynologically, the monotypic American section Tonduzia appears to be most related to the Malesian/Australian/Pacific sections Monuraspermum and Dissuraspermum, and not to the African species of section Alstonia.     

Pollen morphology of JapaneseSymplocos (Symplocaceae)

The pollen morphology of all 23 Japanese species ofSymplocos (1 of subgenusEusymplocos, and 22 of subgenusHopea) was comprehensively studied using LM, SEM and TEM, and found to be classifiable into two types (Type I and II) primarily on the basis of wall structure. Type I, characterized by a thick tectum lacking a supratectal structure and reduced columellae, occurs in subgenusEusymplocos, while Type II, characterized by a thin tectum with a supratectal structure and generally distinct columellae, occurs in subgenusHopea. Resemblances in wall structure suggest a closer relationship of subgenusEusymplocos to subgenusMicrosymplocos as well as of subgenusHopea to subgenusEpigenia. This fact contradicts the earlier proposed infrageneric classification, and may require its revision. Within Type II, five subtypes are recognized primarily on the basis of sculpture combined with other pollen characters. Systematic value of sculpture (i.e., subtype), aperture morphology and “globules”, as well as certain species relationships based on those characters, are also discussed.     

Pollen morphology of Gontortae (Acanthaceae)

Variation in pollen morphology is described and illustrated for 36 genera of Acanthaceae with contorted corolla aestivation. A parsimony analysis of pollen characters is presented.     

Pollen morphology of Trichosanthes (Cucurbitaceae)

The pollen morphology of 37 species of Trichosanthes was examined, using light microscopy, and scanning and transmission electron microscopy. On the basis of the diverse exine ornamentation it is possible to distinguish five pollen types. With aperture characters, two of them can be subdivided into subtypes. Two types can be characterised with ultrastructural features as well. It appeared that several of the types (alt. subtypes) correspond very well to existing macromorphological groupings. The most deviating type, including only the monotypic section Trichosanthes (T. cucumerina), shows verrucate ornamentation, a thick granular infratectum and a thin, indistinctly delimited nexine. It is similar to that of the Madagascan genus Tricyclandra.     

Pollen morphology of Broussonetia (Moraceae)

The pollen of seven species of Broussonetia (including Section Allaeanthus) and one species of Malasia were examined with light, scanning and transmission electron microscopy. The pollen of all species is diporate with slightly annulate pores, and scabrate exine sculpturing. The pollen is small and all species have a columellate wall structure. The closely related genus Malasia is similar to Broussonetia. The similarity of the pollen in Section Broussonetia and Section Allaeanthus suggests that Allaeanthus be retained in the genus Broussonetia.     

Pollen morphology of the genus Paliurus (Rhamnaceae)

The pollen morphology of the genus Paliurus and the 5 species it comprises is described. Consistent with the general morphological pattern of the family Rhamnaceae, the pollen grains of Paliurus are uniformly isopolar, radially symmetrical, 3-(zono)-colporate and angulaperturate. Despite this general infrageneric uniformity, certain differences and trends can be recognized with respect to pollen size, shape, and tectum architecture.     

Pollen grain morphology ofCoris (Primulaceae)

Pollen grain morphology, sculpturing, and wall ultrastructure are investigated in two species ofCoris (Primulaceae),C. monspeliensis L. andC. hispanica Lange. The study includes both acetolysed and unacetolysed pollen. No evidence of any major palynological difference is recorded between these two species, apart from a somewhat larger pollen inC. monspeliensis. However,Coris can be distinguished from the remaining members of thePrimulaceae by the conjunction of relatively large pollen grains, prominent margo, and particular tectal pattern causing a reticulate surface with minute luminal perforations decreasing towards the colpi. From both these distinctive features, and others typically primulaceous, some evolutionary considerations are inferred. Finally, the higher proportion of irregular grains inC. hispanica is interpreted in light of environmental stress.