Pollen morphology and evolution in the genus Orobanche L. s.l. and its allied genera (Orobancheae/Orobanchaceae) in Turkey

The pollen morphology of 120 samples of the tribe Orobancheae, representing four genera and 40 species of Cistanche, Diphelypaea, Orobanche and Phelipanche native to Turkey, has been studied by light and scanning electron microscopy. Pollen of the tribe Orobancheae is typically isopolar, radially asymmetrical, oblate spheroidal or prolate and belongs to one of the following basic pollen types: inaperturate, tricolpate and syncolpate. Also, pollen heteromorphism is widespread among pest species of Orobanche and Phelipanche. Pollen characters display considerable variation among genera and species, but some characters are significant at the levels of genera and sections. The results of the SEM study show that there are various exine ornamentation types in these genera. The obtained results support the division of the traditionally circumscribed genus Orobanche sensu lato into two genera, Phelipanche and Orobanche. The pollen morphological features are discussed on the basis of molecular phylogeny of the taxa.     

Seed morphology of Iranian annual species of Euphorbia (Euphorbiaceae)

Euphorbia (Euphorbiaceae) is one of the largest and most diversified cosmopolitan genera of flowering plants. South‐west Asia is a major centre of diversity and contains c. 65 annual species, 35 of which occur in Iran. In this article, the seed morphology of all Iranian annual species was studied, including E. aulacosperma and E. rhabdothosperma, both new records for Iran. Quantitative and qualitative macro‐ and micromorphological features of seeds and caruncles were investigated using stereomicroscopy and scanning electron microscopy. Caruncle characters (shape, size, colour) and seed characters (shape, size, colour, ornamentation) are often constant and useful in identification and classification. An identification key and scanning electron micrographs are provided for all known Iranian taxa. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 167 , 212–234.     

Seed morphological diversity of Pedicularis (Orobanchaceae) and its taxonomic significance

Mature seeds of 109 species of Pedicularis representing 13 groups according to Tsoong’s infra-generic classification were investigated using light microscopy (LM) and scanning electron microscopy (SEM). The largest seeds occurred in P. superba (4.82 ± 0.32 mm × 2.18 ± 0.18 mm) and the smallest in P. crenata (0.95 ± 0.16 mm × 0.72 ± 0.08 mm). The individual seed weight ranged from 0.20 to 9.52 mg. There were two types of primary ornamentation, i.e. reticulate and undulate. Reticulate seeds were found in all examined species except for P. pantlingii and P. confluens. The reticulate seeds were divided into three subtypes, i.e. cristate-reticulate, regular-reticulate and membranous-reticulate. Among them, the cristate-reticulate and the undulate primary ornamentation are firstly reported. The inner tangential wall ornamentation was categorized into granulate, ruminate or striate. Seed characters seem to support the transfer of Pedicularis to Orobanchaceae from traditional Scrophulariaceae. Seed length, individual seed weight, primary ornamentation and inner tangential wall ornamentation were considered as potentially useful characters for infra-generic classification. Non-metric multidimensional scaling (NMDS) analyses indicated a clustering of some species in group 1 (Sceptrum) and all species in group 6 (Cyathophora), respectively. However, seed data were not highly congruent with Tsoong’s classification for delimitation of existing groups. Some characters, such as seed shape, primary ornamentation, inner tangential wall ornamentation and epidermal cell shape could be applied to identification of some species in this genus.     

Seed morphology under SEM and light microscopy in Kansas Juncus (Juncaceae)

Seed morphology was studied in 15 species of four subgenera ofJuncus occurring in Kansas, to determine if seeds provide traits useful in assessing systematic relations within the genus. In this study seed size and shape were of limited value, while surface ornamentation of the hard inner seed coat provided encouraging results. SubgenusPoiophylli showed little variation in surface ornamentation among taxa; similar ornamentation was observed in subgenusGenuini. SubgeneraGraminifolii andSeptati were separately distinct with the taxa in theSeptati forming a continuum of variation.     

Recognition of root exudates by seeds of broomrape (Orobanche and Phelipanche) species

Background and Aims

The long co-existence of broomrapes and their hosts within the same environment has culminated in a strong adaptation and effective parasitism. As a first step of specialization in the parasitic process, seed receptors of parasitic plant species vary in their ability to recognize compounds released by their hosts. This work aims to investigate potential patterns for the reception requirements needed to activate germination within Orobanche and Phelipanche species.

Methods

Induction of the germination of seeds of nine Orobanche and Pheliphanche species by root exudates of 41 plant species was studied and subjected to biplot multivariate analysis.

Key Results

A high level of specialization in root exudate recognition was found in Orobanche densiflora, O. gracilis and O. hederae, which germinated almost exclusively in contact with root exudates from the plants they infect in nature. At the opposite extreme, Phelipanche aegyptiaca, P. ramosa and O. minor were highly generalist, germinating when in contact with the root exudates of most plant species. Orobanche crenata, O. cumana and O. foetida showed intermediate behaviour.

Conclusions

A universal germination stimulant for all broomrape species has not being identified to date. The synthetic stimulant GR24 is active against most of the weedy broomrape species, but fails with the non-weedy species tested in this study and with the very recent weedy species O. foetida. In addition, germination behaviour of broomrape species depends on the crop plant tested. Weedy broomrapes with a broad host spectrum respond better to the different exudates released by a wide range of crops and wild species than do non-weedy broomrapes, which have a narrow host spectrum and are more restricted to their host range. Root exudates of many plant species were active in stimulating germination of seeds of Orobanche and Phelipanche species for which they are not described as hosts, representing interesting examples of potential trap crops.Key words: Xenognosis, broomrape, root exudate, germination, Orobanche, Phelipanche     

Numerical analyses of seed morphology and its taxonomic significance in the tribe Nigelleae (Ranunculaceae)

We examined the seed morphology of Nigella, Garidella and Komaroffia to aid systematics and taxonomy. The seeds of 21 taxa in 20 species from Mediterranean and West Asian countries were studied using both zoom stereo and scanning electron microscopy (SEM). Principal coordinate analysis (PCoA) and unweighted average linkage analysis (UPGMA) were performed to assess the contribution of seed characters to the taxonomy of the tribe. Representative pictures from zoom stereo microscopy and SEM studies and measurement of seeds are presented. Most studied species showed unique seed surface sculpturing features, and seed shape, size and surface sculpturing separated the studied taxa into five main groups. However, the variation in seed shape and color were found to be in conflict with the generic taxonomy while macromorphological characters were found more congruent with the sectional taxonomy than with the generic taxonomy. Five main types of seed ornamentations – rugulose + striate, granulate, smooth, rugulose and mucronulate – were identified. Patterns in seed micromorphology strongly supported the sectional level taxonomy of Nigella. Two of the three sections of the genus were found to be well differentiated in terms of seed characters. Furthermore, seed morphology alone provide good support to Garidella as a distinct genus, but shows less taxonomic value for Komaroffia.     

Seed morphology in the tribe Chloraeeae (Orchidaceae): combining traditional and geometric morphometrics

Previous work on orchid seeds has shown that characters associated with the seed coat may be useful for classification and phylogeny at a suprageneric level. The seed morphology of several species of the tribe Chloraeeae was analysed using traditional morphometrics, and the seed shape was studied, for the first time, using tools of geometric morphometrics. Seed characters were evaluated by their discriminative power and the information they may provide in a phylogenetic context. By contrast with previous findings, seed shape resulted in a continuum among the taxa studied, and in only a few cases could genera or groups of species be discriminated on the basis of shape. However, seed size, expressed as centroid size, was a variable character and informative at a phylogenetic level. Traditional measures of seed coat, mainly those of seed coat cells, were also helpful for the discrimination of genera and species, agreeing with previous statements about their utility in taxonomy and phylogeny. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 171–183.     

Micromorphological studies on seeds of orobanche species from the iberian peninsula and the balearic islands, and their systematic significance

BACKGROUND AND AIMS: Previous research has made clear the intrinsic taxonomic difficulties in identifying species in the genus Orobanche. The aim of this study, therefore, was to investigate the systematic utility of seed characteristics. METHODS: Light and scanning electron microscopy was used to examine the seeds of 33 taxa of Orobanche from the Iberian Peninsula and the Balearic Islands. KEY RESULTS: Characters such as size, shape and ornamentation of the seeds were not found to be very useful in differentiation of taxa; however, other characters of the epidermal seed coat cells proved to be very helpful in this respect. Ornamentation of the periclinal walls could be used to discriminate four morphological types. Other features related to the anticlinal walls of the cells, such as thickness, presence/absence of a narrow trough, or relative depth, all contributed to the characterization of a large number of species. CONCLUSIONS: The usefulness of micromorphological studies on seeds of Orobanche in relation to differentiating taxa is demonstrated, and a key is provided to distinguish species or groups of species.     

柃属植物种子微形态特征及其系统学意义

利用扫描电镜对35种1变种柃属(Eurya)植物种子的微形态特征进行了研究,并采用相对大小(长×宽)RS值和种皮表面纹饰作为种子形态比较的特征参数。结果显示,柃属种子根据相对大小RS值可划分为小型(RS<1.0),中型(1.03.0)三个等级,最小的种子相对大小不足0.5,最大的种子相对大小超过10;种皮表面纹饰分为负网纹和网纹两种类型,网纹类型在网眼的方向性、网眼形状、网眼深度、网脊特点等方面呈现出种间多样性,可用于类群的比较和鉴别。文中同时还探讨了种子大小及种皮微形态在属内的系统发育关系,推测了种皮表面纹饰的演化路线,研究结果表明种子的微形态特征对本属植物系统分类及进化研究具有重要意义,可为属内一些关键种系统位置的分析提供重要佐证。     

Taxonomic importance of seed morphology in Gentiana (Gentianaceae)

The seeds of Gentiana show high diversity in size, shape and surface pattern. Until now, seeds of only a limited number of taxa have been studied in detail and their utility in the subgeneric classification of Gentiana has not been evaluated. In this study we investigated seed micromorphology of the poorly known sections Pneumonanthe, Frigidae and Isomeria. In order to evaluate the relevance of seed sculpturing for taxonomy, we selected qualitative characters of seed shape and testa ornamentation of all documented sections and performed cluster analyses based on presence and absence of coded characters. Several new scanning electron microscopy pictures of seeds provided a number of valuable characters for the subgeneric differentiation of Gentiana. The results of the cluster analyses of seed characters generally support the sectional classification given by former authors. However, the European Gentiana asclepiadea does not group together with other taxa of section Pneumonanthe, but clusters near to the strictly European section Gentiana. Gentiana froelichii, endemic to the south‐east Alps and treated traditionally within section Frigidae, clusters together with taxa of the European section Ciminalis. Our results reveal that seed micromorphology supports the reassignment of some taxa incertae sedis within Gentiana. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162 , 101–115.     

Systematic implication of seed micromorphology in Arenaria (Caryophyllaceae) and allied genera

Variations in seed micromorphology of 64 taxa of Arenaria and allied genera were examined using scanning electron microscopy (SEM) in order to evaluate their diagnostic value for systematic studies in the genus and providing additional evidence on delimitation of natural groups. Significant diversity was found in seed coat morphology both among and within genera. Size, color, and shape of seeds appear to be of low importance at species level but provide useful evidence at generic rank. Cerastium and Stellaria are well distinguished from Arenaria by serrate seed margins and solid columellae on testa cells. The sculpturing pattern renders most characters potentially applicable in taxonomy and phylogeny assessment in Arenaria. The studied taxa show four basic types of sculpturing, viz. colliculate, rugose, papillate, and smooth. The colliculate type which is characteristic for the core group of Arenaria (A. subg. Arenaria) can be further divided into five subtypes. The smooth seed surface with indistinct cell boundaries represents a synapomorphy for A. subg. Leiosperma, whereas the winged seeds along with rugose surface characterize subg. Odontostemma. Otherwise seed micromorphology rarely provides adequate evidence for separation of natural groups, especially at sectional rank. We hypothesize that the seeds are highly polymorphic in certain groups of taxa showing recent adaptive radiation, such as the annual species of Arenaria, and do not provide strong support for natural groups within the genus.     

Seed-coat microsculpturing and its systematic application in Isatis (Brassicaceae) and allied genera in Iran

In order to examine the systematic application of seed-coat microsculpturing in Isatis, seed surfaces of 23 species (41 populations) in four genera of tribe Isatideae were examined using scanning electron microscopy (SEM). Eight types of basic ornamentation patterns were recognized among the studied specimens. Of these, the reticulate–areolate type was the most common and was found in the genera Isatis, Pachypterygium, Samerari and Tauscheria and 15 species (e.g., I. cappodocica, I. kotschyana and I. tinctoria). The reticulate type, the second most frequent, occurred in 7 species while other types each were represented by only one or 2 species. Although different populations of a given species show similar seed-surface sculpturing in most cases, in some polymorphic species like I. cappadocica and I. kotschyana these patterns were variable among populations. To some extent the variation corresponds to infraspecific taxa for some species, but the differences are not significant enough to be useful in the delimitation of the subspecies recognized by previous workers. Moreover, seed-coat characters do not support the separation of genera Isatis, Pachypterygium, Sameraria and Tauscheria.     

国产藜科14种植物种皮微形态特征比较研究

应用扫描电子显微镜和光学显微镜观察了中国产藜科(Chenopodiaceae)5族10属14种植物的种子形态和种皮微形态结构。观察结果表明:供试的14种藜科植物的种子多为卵形和圆形,少数为双凸镜形;种皮表面都具有网状纹饰,包括浅网纹、负网纹和穴状网纹。种皮可分为膜质和壳质2类,其中,膜质型种皮表面不光滑,除网状纹饰外,还有瘤状或褶皱状等纹饰,网眼无规则,纹饰排列无序,猪毛菜族(Salsoleae C.A.Mey.)的松叶猪毛菜(Salsola laricifolia Turcz.ex Litv.)及樟味藜族(Camphorosmeae Moq.)的地肤〔Kochia scoparia(L.)Schrad.〕、全翅地肤(K.krylovii Litv.)、黑翅地肤(K.melanoptera Bunge)、雾冰藜〔Bassia dasyphylla(Fisch.et Mey.)O.Kuntze〕、钩刺雾冰藜〔B.hyssopifolia(Pall.)O.Kuntze〕、樟味藜(Camphorosma monspeliaca L.)、兜藜(Panderia turkestanica Iljin.)和棉藜(Kirilowia eriantha Bunge)均属此类;壳质型种皮表面近光滑,网眼规则,排列整齐有序,少数为不规则浅穴,网脊平而不明显或凹陷,滨藜族(Atripliceae C.A.Mey.)的滨藜〔Atriplex patens(Litv.)Iljin.〕、碱蓬族(Suaedeae Reich.)的角果碱蓬〔Suaeda corniculata(C.A.Mey.)Bunge〕、纵翅碱蓬〔S.pterantha(Kar.et Kir.)Bunge〕和异子蓬(Borszczowia aralocaspica Bunge)以及藜族(Chenopodieae C.A.Mey.)的刺藜(Chenopodium aristatum L.)均属此类。各族之间种皮微形态结构也有一定的区别。根据种皮微形态,地肤属(Kochia Roth)与雾冰藜属(Bassia All.)的关系较近,属的界限和部分种类的亲缘关系需要进一步界定。藜科植物种皮表面大部分凹凸不平,这种结构可能与荒漠干旱生境下吸收和保留水分有关。     

Morphology of pollen and orbicules in the tribe Spiraeeae (Rosaceae) and its systematic implications

This study provides pollen data for 38 representative taxa belonging to all nine genera in the current classification of the tribe Spiraeeae (Rosaceae) including the monotypic Korean endemic genus Pentactina, and considers the distribution of orbicules for the first time. Pollen morphology and wall stratification were investigated using light, scanning electron and transmission electron microscopy. Spiraeeae pollen grains are small to medium in size (P = 6.9–34.0 μm, E = 7.1–28.0 μm), oblate to prolate in shape (P/E = 0.66–1.48) and tri-colporate. Spiraeeae pollen is generally characterised by striate sexine ornamentation, but four ornamentation types are recognised based on the length and direction of the ridge patterns. The observed variation in sexine ornamentation is particularly valuable at the generic level. The exine stratification of the representative Spiraeeae studied is similar and characterised by unbranched columellae and a continuous endexine. Orbicules are present in three genera of the tribe (Luetkea, Sibiraea and Xerospiraea). Orbicule distribution patterns indicate that the absence of orbicules is a synapomorphic condition of the more derived clade, comprising Pentactina + Petrophytum + Kelseya + Spiraea.     

Comparative seed morphology of <Emphasis Type="Italic">Leandra</Emphasis> (Miconieae,Melastomataceae)

The seed morphology of 79 species of neotropical Miconieae (Melastomataceae) is presented. These species have been chosen, in majority, from the polyphyletic genus Leandra. A few other species from the polyphyletic genera Miconia, Ossaea, and Clidemia were also sampled, because of potential similarities. Sixteen morphological seed types are defined after analysis through light microscopy and scanning electron microscopy. The seed morphology appears to possess a great deal of variability on the level of the overall shape as well as the structure and the surface of the testa. The different types defined here do not match with genera or sections, but rather are composed of species coming from different genera. In comparison with a preliminary molecular phylogeny study done on Leandra, some types of seeds are related to well supported clades. In some cases seed morphology corresponds with natural groups of species, thus being of high phylogenetic importance.     

罗布麻与大花罗布麻种了微结构特征

罗布麻（Ａｐｏｃｙｎｕｍ ｖｅｎｔｒｍ Ｌ．）和大花罗布麻（Ｐｏａｃｙｎｕｍ ｈｅｎｄｅｒｓｏｎｉｉ（Ｈｏｏｋ．ｆ．）Ｗｏｏｄｓｏｎ）分别属于夹竹桃科罗布麻属（Ａｐｏｃｙｎｕｍ Ｌ．）和白麻属（Ｐｏａｃｙｎｕｍ Ｂａｉｌｌ．）。其外部形态区分明显,但种子微结构特征却颇为相似。种子形状、颜色相同,大小相近;种子表面基本纹饰均为网穴状,次级纹饰均为颗粒状。     

Pollen morphology of the family Cistaceae in Egypt and its systematic significance

The pollen morphology of 11 species (including two subspecies and two varieties) belonging to two genera (Helianthemum and Fumana) of the family Cistaceae in Egypt was studied using light and scanning electron microscopy.Pollen grains of the studied taxa were found to be radially symmetrical and tricolporate.Pollen size,shape,apertures,and exine ornamentation characteristics were valuable parameters among the studied taxa.The largest pollen size was recorded in H.salicifolium and the smallest one observed in H.kahiricum subsp,schweinfurthii.Pollen shape in the Egyptian taxa varied from (sub-)prolate to prolate spheroidal,but F.arabica is different in having sub-oblate grains.The pollen data confirm that H.lippii and H.sessiliflorum are very closely related species.Pollen sculpture was useful in distinguishing between H.vesicarium var.vesicarium and H.vesicarium var.ciliatum.Three main pollen types of exine ornamentation were recognized:retipilate; reticulate to verrucate; and striate.Based on palynological data,a key for the studied taxa is suggested.     

Nutlet micromorphology of Iranian Nepeta (Lamiaceae) species

To evaluate nutlets characteristics for systematic relationships, a comprehensive morphological and micro‐morphological study of the nutlets of 16 Iranian taxa of Nepeta (Lamiaceae) was conducted using scanning electron microscopy (SEM). Differences in surface ornamentation, size, shape and color were observed between the species. The studied taxa were categorized in two basic types based on surface ornamentation: non‐sculptured (smooth‐type) and sculptured nutlets. The non‐sculptured nutlets type could be further divided into four sub‐types, including smooth, granulate, undulate‐cellular and reticulate. In the sculptured nutlets, three subtypes of tuberculate, tuberculate‐cellular and verrucate were recognized. The shape of nutlets were described as oblong, ovoid‐oblong, oblong‐linear, to elliptic‐oblong and their size range are 1.2–2.0 mm in length and 0.5–2.0 mm in width. Based on micrographs, the areole form and location were defined as bi‐lobed, straight, basal, sub‐basal or lateral. Nutlet micromorphological characteristics such as surface ornamentation can be useful for classification and identification of e.g. medicinal species of Nepeta in Iran.     

Micro‐morphological characteristics of seed and ovary trichomes of Iranian Glaucium Mill. species (Papaveraceae) and their taxonomic importance

Seeds and trichomes of 15 taxa of the genus Glaucium distributed in Iran were examined by light microscopy (LM) and scanning electron microscopy (SEM). The seeds are slightly shiny to rather shiny, however, strongly shiny seeds were also observed in some species (G. corniculatum and G. grandiflorum). The basic shape of the seeds is semicircular to reniform, but reniform and elongated reniform seeds were found in G. oxylobum and G. elegans, respectively. The sculpturing of the testa surface are verrucate–rugulate (most frequent type), verrucate–granulate, verrucate–perforate, verrucate–lineolate, rugulate–granulate, rugulate and ocellate. Elongated polygonal epidermal cells dominate in most taxa investigated, but there are polygonal and irregular polygonal cells in a few taxa. The investigated species have two types of trichomes on the ovary: tuberculate and non‐tuberculate. The non‐tuberculate trichomes are of two subtypes: pilose and squamiform. Based on the number of cells, the squamiform trichomes were further divided into two groups (uniseriate and multiseriate) differing in shape, size and cellular structure. The results show that the micro‐morphological characteristics of seed and ovary trichomes provide useful and significant information for separation of species and taxa within species and a diagnostic key to the taxa is provided.     

Taxonomic importance of seed macro‐ and micro‐morphology in Abelmoschus (Malvaceae)

Seed morphology of Abelmoschus is known to be variable, but patterns of variation have never been critically studied. We studied seed macro‐ and micro‐morphological characters, including seed shape/size, seed coat pattern and trichome density/structure in multiple samples to evaluate the taxonomic significance of seed characters. Among the studied characters, seed shape and trichome structure were found to have major taxonomic importance and proved to be valuable characters for separating taxa. Two main seed types were present: seeds with deciduous trichomes and seeds with persistent trichomes. These characters offer significant evidence to the distinctness of certain species (A. esculentus, A. moschatus subsp. moschatus, A. moschatus subsp. tuberosus, A. crinitus and A. angulosus). Further, our results indicate that A. moschatus subsp. tuberosus should be maintained as a separate subspecies while A. manihot subsp. tetraphyllus var. pungens may be merged in A. angulosus. No significant intraspecific variation was observed, except in A. esculentus. We conclude that seed coat sculpturing and seed trichomes do indeed provide stable and diagnostic characters for many morphologically closely related taxa of Abelmoschus and that LM/SEM techniques can be useful in solving systematic problems and management of Abelmoschus genetic resources.