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.     

旌节花科及其相关类群花粉形态的研究

对旌节花科及其相关类群五桠果科、猕猴桃科、水东哥科、金莲木科、省沽油科和山茶科等7科19属37种花粉进行了光镜（LM）和扫描电镜（SEM）的观察和比较。其中有些种类是第一次观察和报道。研究表明,上述各科花粉多为近球形至球形,少数近扁球形或近长球形。极面观三裂圆形或近三裂圆形。直径20－30（－35μm）,但厚皮香亚科和省沽油科银鹊树属Tapiscia的花科特别小,仅12.5-20μm。3孔沟,罕有3沟或4孔沟。外萌发孔（沟）相对地较长而宽,内孔多数较发达。花粉外壁纹饰变化大,从模糊而粗糙的细突起到皱波状纹饰,细孔状纹饰,蜂巢状－穴状纹饰,穴－网状纹饰,网状纹饰和颗粒状纹饰等。从形状、大小、萌发孔类型和外壁纹饰的比较看,虽然上述各科花粉均在不同程度上具有一定的相似性,但其中以旌节花科、省沽油科和山茶科中厚皮香科的花粉具有更多的相似性,尤其表现在外壁纹饰特征上。就孢粉学而言,也许旌节花科与省沽油科和山茶科中的厚皮香亚科的关系相对地较为密切。不过,其孢粉学特征所表现出的亲缘关系似乎不如在分子生物学中所表现出的明显。     

A Study on Pollen Morphology of Tribe Rhamneae (Rhamnaceae)in China

Pollen morphology of 25 Chinese species, representing 6 five genera in the tribe Rhamneae of Rhamnaceae, was examined under LM and SEM. Pollen grains are subspheroidal or suboblate, obtuse-triangular in polar view, 3-colporate, with the polar axis (P)10.4-28.7μm long and equatorial axis (E) 11.3-30.5μm long, P/E = 0.81-1.11. Colpi generally narrow and long, ora lalongate, with two ends connected with the thinned part of exine, forming a H-shape. Four thickenings were observed where colpi and ora cross, but sometimes the thickenings were indistinct or formed a ring. The stratification indistinct. The ornamentation of exine obscure or indistinctly reticulate under LM, but rugulose, short-striate, rugulose-foveolate or reticulate under SEM. The exine ultrastructure of Rhamnus ussuriensis was examined under TEM. It consists of imperforate tectum, granular layer, foot layer and endexine. The tectum is rather thick with uneven surface, while the granular layer is rather thin. A key to the genera based on pollen characteristics is provided and the general pollenmorphology of five genera, i.e. Sageretia, Rhamnus, Hovenia, Colubrina and Alphitonia, is described respectively. Based on pollen size, the four thickenings and the ornamentation, the five genera under study may be distinguished from each other. For example, pollen grains are smaller in Sageretia; the four thickenings are larger and distinct in Hovenia and Alphitonia. However, the ornamentation is short-striate under SEM in Hovenia and Alphitonia, while reticulate in the Colubrina and Rhamnus ( Subgen. Rhamnus) .Two different concepts of Rhamnus exist among taxonomists. Heppeler and Suessenguth divided Rhamnus into two subgenera (Subgen. Frangula and Subgen. Rhamnus), whereas Grubov separated Subgen. Frangula from Rhamnus as an independent genus. According to the pollen morphology, the separationis reasonable.     

Pollen Morphology of Loxostemon (Cruciferae) in China

The present paper deals with the pollen morphology of 10 species and 1 variety of Loxostemon in China. The pollen grains were all examined under light microscope. The pollen grains of Loxostemon are subspheroidal, spheroidal or prolate, 18--33×11.8-28 μ in size, 3-colpate, colpi 15-21 μ long and 1-2 μ wide. The exine is 1.5-3 μ thick with two indistinct or distinct layers. All the pollen grains are generally reticulate under light microscope. They are distinctly or obscurely and finely reticulate. L. axillus and L. repens are generally similar in gross morphology, but the pollen grains of these two species are different. The pollen grains of L. axillus are regularly polygonally reticulate, colpi are acute-ended and the exine is about 3 μ thick, whereas those of L.repens are irregularly polygonally reticulate, colpi are enlarged at both ends and the exine is about 2.8 μ thick. L. incanus and L. stenolobus appear to have similar gross morphology, but the pollen grains of the former have exines with two distinct layers and a densely and finely reticulate ornamentation and those of the latter have exines with two indistinct layers and a flexuosely reticulate ornamentation.     

Pollen Morphology of Microula Benth. and Allied Genera (Boraginaceae)

Pollen grains of 16 species of Microula Benth. and six species of three related genera were examined under LM and SEM, and four of them also under TEM. Pollen grains of Microula and three related genera are dumb-bell-shaped, 3-colporate apertures alternate with three pseudocolpi. Pollen grains are very small,ranging from 12.18 x 7.13 μm to 6.36 x 3.66μm. In general, colpi with os are wider and shorter, rhomboid, but sometimes they are equal to pseudocolpi in length. Colpus margins are regularly or irregularly tooth-like. The surface of colpi is psilate or processed. Ora are circular or lalongated in outline, protruded or not; surface of os membrane is smooth or scabrid. The exine is usually indistinctly layered under LM. The exine surface is psilate, and more or less perforate. TEM examination shows that the pollen wall is differentiated into exine and intine: the exine includes ectexine and endexine, while the ectexine consists of tectum, columellae and foot-layer. However, there are differences in constriction of equatorial area, apertural characters, ornamentation and exinous ultrastructure between these genera. Pollen morphology indicates that the genus Microula Benth. is primitive, directly related to the genus Actinocarya Benth .; the genus Asperugo L. Is more advanced. The genus Eritrichium Schrad. which has two ora or one os and is anisopolar, represents the most advanced group among them. Noteworthily, the diorate phenomenon is found for the first time not onlyin the genus but in the family Boraginaceae.     

Pollen morphology and phylogenetic relationships in neotropical Phyllanthus (Euphorbiaceae)

In order to provide new insights into phylogenetic relationships among the neotropical taxa of Phyllanthus , 28 illustrations are provided of the pollen grains of 22 selected species studied from 11 sections of the subgenera represented in the neotropics. Special attention has been given to subgenus Conami because of its variability in pollen morphology: of eight species illustrated, the apertures are diploporate colpi in three species and pores in five species; exine ornamentation is vermiculate in two species and pilate in the other six species. The six species in the neotropical sections Pityrocladus and Microglochidion (subgenus Emblica ) are characterized by prolate grains with an increased number of colpi (4–8). Of particular interest are species in which the pollen exine is clypeate (with exine shields); clypeate pollen grains are illustrated in two species of subgenus Xylophylla and in one species of section Cyclanthera that has unique exine shields with single central pila. The pollen of the one Brazilian phylloclade-bearing species illustrated (in section Choretropsis ) has 3-colporate grains with reticulate exine, typical for subgenus Phyllanthus , and very different from the clypeate grains of the West Indian phylloclade-bearing species in section Xylophylla . This pollen evidence clearly demonstrates homoplasy in the origin of phylloclades in Phyllanthus . Pollen morphological data suggest that the neotropical taxa of Phyllanthus have arisen following colonization from Africa (subgenus Kirganelia ) and Asia (subgenus Emblica ). © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 138 , 325–338.     

Studies on the Pollen Morphology of Tribe Zizipheae of Rhamnaceae in China

Pollen morphology of Chinese 19 species representing 6 genera in the tribe Zizipheae Brongn., Rhamnaceae, was examined under light microscope and scanning electron microscope. The pollen grains oblate or suboblate, rarely subspheroidal. Polar axis 13.1-26.1μm long, equatorial axis 16.5-29.6μm long, 3-colporate, colpus generally narrow, ora lalongate, with two ends connected with the thinned part of exine, forming a H-shape. There are 4 thickenings where colpi and ora pass across, or sometimes the thickenings indistinct, forming a ring. Stratification couspicuous or inconspicuous. Ornamentation of exine obscure, rarely obscurely reticulate under light microscope, but conspicuously fine-reticulate, finely reticulate-foveolate, foveolate, striate-reticulate and shortly striate under scanning electron microscope. A key to the genera based on pollen grains is provided and the general morphology of 6 genera: Paliurus, Ziziphus, Chaydaia, Berchemia, Berchemiella and Rhamnella are described. Based on 4 thickenings and H-shape, pollen grains of the tribe Zizipheae may be divided into two groups: 1. the four thickenings rather larger and conspicuous, or stretched along the colpus in some species, H-shape distinct, e.g. in Berchemiella, Chaydaia and Rhamnella, and 2. the four thickenings smaller, sometimes forming a ring, H-shape more or less conspicuous, e.g. in Berchemia, Paliurus and Ziziphus. With respect to the concept of the genera Berchemiella and Berchemia, there were two different ideas among a number of taxonomists. H. Koidzumi, J. Ohwi and S. Kitamura place the former in Berchemia as a section, but on the contrary, T. Nakai, T. Yamazaki and K. Suessenguth consider Berchemiella and Berchemia as two separate genera. The data from pollen morphology support the latter treatment. Berchemia is closely related to Berchemiella, Chaydaia and Rhamnella in the habit and the floral morphology, but differs from the others by its disc well-developed, eularged and becoming cup-shaped in fruit. They are also different from each other in the characters of pollen grains. T. Yamazaki places the genus Chaydaia in Rhamnella as a section, but according to the pollen morphology to treat Chaydaia and Rhamnella as two independent genera woild be reasonable.     

山茶属花粉外壁表面微形态特征的研究

在前人研究的基础上,利用光学显微镜和扫描电镜观察了山茶属17个组34个代表种（含变种）的花粉形态;按照韦仲新划分山茶属花粉类型的标准,对其进行归类,所有花粉分为3类：颗粒状至皱颗粒状纹饰、皱沟状纹饰和穴－网状纹饰;发现1种新的花粉类型：拟穴－网状纹饰。本文还对山茶属的某些分类学问题作了初步探讨。     

Pollen morphology inParis and its related genera

Pollen grains ofParis, Medeola, andScoliopus have been examined with light, scanning electron, and transmission electron microscopies.P. quadrifolia L.,P. verticillata Bieb.,P. delavayi Franch. andP. polyphylla Smith have monosulcate pollen characterized by psilate, foveolate or reticulate exine sculpture. In contrast to the former species,P. japonica (Fr. et Sav.) Franch. andP. tetraphylla A. Gray have monosulcate pollen with gemmate (rarely rugulate) exine.Medeola has monosulcate pollen with reticulate exine that is distinct from that ofParis. Scoliopus has monosulcate pollen characterized by a peculiar reticulate exine pattern. The palynological evidence suggests thatParis andTrillium are closely related to each other, andMedeola andScoliopus should be separated fromParis andTrillium.     

羊蹄甲属中国特有种的花粉形态学

对羊蹄甲属植物11种中国特有种的花粉形态进行了研究。结果表明,花粉萌发孔类型均为三孔沟,少数还有合沟;花粉均具半覆盖层,表面纹饰有皱波状、皱波状-穿孔、疣状、孔穴-穿孔、穿孔-网状。依据Larsen(1975)的划分,这11种植物的花粉隶属于Integrifolia型、Glauca型和Curtisii型,我们根据花粉纹饰的差异在Integrifolia型下进一步划分了Auma亚型和Paucinervata亚型。     

Pollen Morphology of the Genus Malus and Its Taxonomic and Evolutionary Significance

The pollen morphology of 26 species and 5 hybrids of the genus Malus was investigated with aid of SEM. It is found that the pollen morphology of Malus is rather similar in shape, size, position and number of aperture and exine sculpture. The characters of polle morphology of sections and series are as follows: Sect. Malus Ser. Baccatae: Striae regular, parallel to colpi, and conjunct at pole; Ser. Pumilae: the same as in Ser. Baccatae, but more or less curved near pole. Sect. Docyniopes: Striae regular and parallel to colpi, but bent near pole. Sect. Chloromeles: Striae irregular, dense and interlock. Sect. Sorbormalus: Striae irregular, sparse and not interlock. Ser. Sieboldiance: pollen grains prolate, with perforation among striae, colpi narrow; Ser. Kansuenses: Pollen grains spheroidal, colpi wide in the middle but narrow at both ends, striae relatively dense and regular, mostly dichotomous, perforation present; Ser. Yunnanenses; Pollen grain spheroidae, colpi wide in the middle but narrow at both ends, striae obviously irregular, less dichotomous, perforation absent. The major evolutionary trend of exine sculpture of pollen may be from densely thin-striate to sparsely striate with perforation. Characters of the exine sculpture of hybrids can be used to recognize the rela-tionship between the parental species.     

天麻抗真菌蛋白对木霉菌丝的作用位点

天麻抗真菌蛋白(Gastrodia Antifungal Protein,GAFP)能强烈抑制腐生真菌菌丝的生长,在天麻限制和防止蜜环菌［Armillariella mellea (Vahl. ex Fr.)Karst.］侵染球茎的防卫机制中起重要作用。本文报告GAFP抗菌机理研究的部分内容——GAFP对木霉菌丝的作用位点。用荧光试剂异硫氰酸荧光素(Fluorescein isothiocyanate,FITC)标记GAFP,试验表明,标记后的GAFP与未标记的GAFP对木霉菌丝生长均有抑制作用。在荧光显微镜下观察GAFP在木霉菌丝上的作用位点,发现被“标记GAFP”作用后的菌丝边缘有荧光,并主要集中在木霉菌丝的顶端和菌丝横隔处,表明GAFP对木霉的作用位点在菌丝的细胞壁上。     

Pollen morphology,ultrastructure and taphonomy of the Neuradaceae with special reference to Neurada procumbens L. and Grielum humifusum E.Mey. ex Harv. et Sond.

Pollen morphology and sporoderm ultrastructure of modern Neurada procumbens L. and Grielum humifusum E.Mey. ex Harv. et Sond. were studied using light (LM) and electron (SEM and TEM) microscopy. Additionally late Holocene pollen of the Grielum-type was studied using LM. Systematic and ecological aspects have been discussed for the family Neuradaceae. The pollen grains of the studied species are characterized by similarities in size, shape, aperture type and differences in exine sculpture (reticulate semitectate exine in Neurada and finely reticulate to foveolate in Grielum) and sporoderm ultrastructure. The cavea in the exine is situated between the ectexine and endexine which are connected near the aperture region only. A combination of the palynological characters of the Neuradaceae (semitectate exine, rather loose columellae, interrupted foot layer, the cavea in the exine) increases the pollen plasticity, allowing considerable changes of the pollen grain volume but still remains insufficient to survive sharp fluctuations in hydration level.     

大风子科13个种的花粉形态

利用光镜和扫描电镜对大风子科 9属 1 3个种的花粉形态进行了观察。花粉形状长球形或圆球形 ,除大风子属 (Hydnocarpus)萌发孔为三拟孔沟 ,其余均为三孔沟 ;外壁纹饰在不同属、同属不同种间表现出明显的多样化 ,基本上可分为粗网状、细网状、穿孔状、穴状4种类型。研究认为花粉形态对于该科与近缘科以及属下的划分具有一定的意义     

Pollen Morphology of the Family Zingiberaceae in China—Pollen Types and Their Significance in the Taxonomy

Pollen morphology of 89 species and 3 varieties belonging to 18 genera (out of 150 spcies in 20 genera) of Zingiberaceae in China was studied under both light microscope and scanning electron microscope. Pollen grains of Zingiberaceae are spherical, subspherical, ovoid and prolate, 36-225 μm in size, nonaperturate or aperturate (spiraperturate, porate). Pollen grains are almost not resistant to acetolysis. The wall is composed of a very thin exine and a thick intine. The exine is psilate, spinate, cerebelloid-areolate, striate, verrucate and foveolate. According to the presence or the absence of aperture and differential ornamentations, two types and six subtypes are recognized: I. The type Nonaperturate: (85 species and 3 varieties in 18 genera). Four subtypes can be recognized within the type based on the characteristics of the exine sculpture. These are: (1) The subtype Psilate, in which, the exine is nearly smooth (including: Hedychium, Curcuma, Kaempferia, Caulokaempferia coenobilis, Boesenbergia rotunda, Stahlianthus, Amomum compactum, Etingera, Hornstedtis, Rhynchanthus). (2) The subtype Spinate, which comprises two groups: (A) The group Short-spinate, pollen grains with smaller spines (Globba), (B) The group Long-spinate, pollen grains with longer spines (Alpinia, Amomum, Plagiostachys, Roscoea, Cautleya, Boesenbergia fallax, Caulokaempferia yunnanensis). (3) The subtype Cereblloid-areolate, pollen grains of which are spherical or subspherical, with cerebelloid sculpture (Zingiber Sect. Zingiber). (4) The subtype Striate, pollen grains of which are prolate or oliveshaped, and striate (Zingiber Setc. Cryptanthium). II. The type Aperturate, in which pollen grains are acetilysis-resistant and possess distinct apertures (mixed colpate-porate or forate), including two subtypes: (1)The subtype Mixed colpate and Porate. Pollen grains are both 3-colpate and 1-3-porate, and usually with one long spiral, two short (straight or slightly curved) colpi and 1-3-poris. The exine is verrucate or not, nearly sinuolate (Costus speciosus, C. tonkinensis, C. lacerus). (2) The subtype porate, whose grains are 6-8-porate and exine is foveolate (Costus megalobractea). The taxonomic significance of the pollen types in the family Zingiberaceae is also discussed.     

COMPARATIVE POLLEN MORPHOLOGY AND TAXONOMIC AFFINITIES IN CYCADALES

Scanning and transmission electron microscopy of pollen grains of 29 species, representing the ten extant genera of Cycadales, has provided valuable insight into their relationships. Pollen grains of these taxa are boat-shaped, monosulcate, and bilaterally symmetrical. They range from narrowly to widely elliptical or subcircular when viewed distally, and have an exine surface of psilate, foveolate, or fossulate. Pollen wall ultrastructure of Cycadales is typically tectate with alveolate∗∗∗spongy exine. The nexine is laminated in all genera. Nexine 1 (footlayer) is present in most species as a thin and often discontinuous layer. There is consistent variation in thickness of the sporoderm layers among the genera but relative uniformity within them. Pollen characteristics are well correlated with macro- and micromorphological features, chromosome numbers, geographical distribution, and postulated pollination mode. A close affinity between Encephalartos, Lepidozamia, and Macrozamia is recognized. Pollen characteristics of the genus Bowenia show some similarity with those of the latter group. Except for two species of Macrozamia which are narrowly elliptic, all of the genera have widely elliptic pollen and share a psilate exine surface and the thinnest sexine with nearly identical arrangement of alveoli. Pollen grains of the species in the genus Dioon exhibit a unique morphology but are more similar to Stangeria than they are to those of taxa in Zamiaceae. The circular outline of the grains and the foveolate exine surface are characters shared by these two genera, but several morphological features distinguish Dioon from Stangeria. Ceratozamia and Zamia share a widely elliptic shape, foveolate exine surface and nearly identical sexine, as well as morphological features and chromosome numbers. They differ from Microcycas in sexine thickness, gross morphology and chromosome numbers. The pollen grains of Cycas circinalis and C. revoluta differ in size and structure of the sexine from all other genera and from each other, substantiating their distinct subgeneric delimitations.     

Palynology of South Indian Zingiberaceae

MANGALY, J. K. & NAYAR, J. 1990. Palynology of South Indian Zingiberaceae. Light microscope studies on pollen morphology of 21 Old World, tropical taxa of Zingiberaceae reveal that an exine is absent only in Kaempferia . A discontinuous exine layer consisting of circular plates joined together at margins occurs in Alpinia galanga and Amomum hypoleucum while all other taxa possess an uninterrupted exine layer which is commonly 0.7 μm to less than 2.0 μrn thick (3.2 μm in Zingiber zerumbet , 2.5 μm in Amomum hypoleucum ). Exine is spinose in Alpinia (smooth in Alpinia sanderae ), Amomum and Boesenbergia , verrucose in Eleltaria , tuberculate to areolate or striate in Zingiber , papillose in Globba and smooth or nearly so in Curcuma, Costus and Hedychiurn . Pollen grains are spheroidal, 50–90 μm in size (35 μm in Globba ophioglossa ), and inaparturate (foraminate in Costus ), except in Curcuma and Zingiber where they are ovoid to ellipsoidal, 70–135 times 60–80 μm in size and sulcate. A lamellated intine, much thicker than the exine, occurs in all, and it is thinner at the apertural region in Curcuma, Costus and Zingiber; in Elettaria and Hedychiurn it is thinner in one or few large scattered circular areas, and in Boesenbergia and Alpinia zerumbet on one side of the grains. Palynologirally Alpinia, Amomum, Boesenbergia, Kaempferia and Zingiber constitute one group while Elettaria, Hedychiurn and Costus constitute another.     

POLLEN MORPHOLOGY AND SYSTEMATIC RELATIONSHIPS AMONG NEW WORLD SPECIES IN TRIBE ANTIRRHINEAE (SCROPHULARIACEAE)

The morphology of mature pollen grains among 12 New World genera in tribe Antirrhineae has been examined with light and scanning electron microscopy. Pollen from 29 American species have mean polar diam that range from 17 to 26 μm, have a tectate structure with perforate, microreticulate, or reticulate surface pattern, and are subspheroidal to prolate, and trizonocolporate with fusiform or narrowly oblong colpi that are free or occasionally fused at the poles. Among the genera, pollen size is positively associated with style length but not haploid chromosome number. Three major morphological categories are recognized based on grain shape, exine structural pattern, and colpus shape. Two of these morphotypes each characterize individual genera (Mohavea, Linaria). The other morphological category includes ten New World genera and has been divided into three subcategories based on variation in lumina diam and intermittent occurrence of fused colpi. Only Antirrhinum and Pseudorontium have species or populations with pollen in more than one subcategory. Concordance of morphological, anatomical, chromosomal, and palynological data suggests that Linaria and Mohavea are best placed in separate subtribes from other native American genera. Compared to Old World taxa in tribe Antirrhineae, the most common pollen type (subspheroidal, microreticulate, apocolpate, fusiform colpi) may be the most primitive. Pollen grains with fused colpi (Antirrhinum p.p., Pseudorontium) and perforate (Mohavea) or reticulate (Holmgrenanthe) structural patterns probably represent derived types.     

POLLEN MORPHOLOGY OF AMPHIANTHUS,ARTANEMA, CURANGA,GLOSSOSTIGMA, AND PEPLIDIUM (SCROPHULARIACEAE-GRATIOLEAE)

Pollen of the scrophulariaceous genera Amphianthus, Artanema, Curanga, Glossostigma, and Peplidium was examined by light and scanning electron microscopy. All have single, isopolar, radially symmetrical pollen grains with equally spaced meridional colpi and columellate exines. Intergeneric differences are established mainly on the differential correlation of colpus number, colpus morphology, and sculpturing of the mesocolpium. The colpi vary in length and range in number from 3 to 6. The colpus membrane can be variously granular, verrucate, rugulate, or spinulose. The exine varies from semitectate and microreticulate or reticulate to tectate and sparsely perforate. It may be psilate or ornamented with supratectal processes ranging from small granules to relatively long spinules or bacules. All the genera examined, with the possible exception of Artanema vs. Amphianthus, are distinguished from one another by pollen morphology, and the grains of both Curanga and Glossostigma have morphotypes not previously reported in tribe Gratioleae. Final taxonomic assessment of the pollen data in the genera examined must await further comparative studies in the Gratioleae and other tribes, but the morphological diversity observed is clearly of potential significance in evaluating specialization levels and clarifying current conflicting interpretations of relationships in these taxa.     

东北杜鹃花属植物花粉形态的研究

利用光学显微镜和扫描电子显微镜对东北杜鹃花属(Rhododendron Linn.)6种, 1变种, 1变型的花粉形态进行了观察和比较研究。该属花粉粒均为四合花粉。四合花粉呈正四面体排列。花粉粒近球形。每粒花粉均具3沟,在四合花粉粒上,相邻花粉粒上的沟相接,有些种可见沟内的萌发孔。光镜下可见花粉外壁为内外两层,厚度约相等。不同的种在花粉粒大小上有区别。在扫描电镜下观察可见不同的种花粉表面具有不同的纹饰。即该属在花粉形态上具有种的特性。