Comparative pollen morphology and ultrastructure of Mentheae subtribe Nepetinae (Lamiaceae)

This study provides new pollen data of 52 representative species belonging to all 12 genera in the currently classification of the subtribe Nepetinae, and considers the possible presence of orbicules for the first time. Pollen morphology and ultrastructure were investigated with light, scanning electron and transmission electron microscopy. Nepetinae pollen is small to large (P = 16–65 µm, E = 17–53 µm), oblate to prolate (P/E = 0.7–1.6) in shape and mostly hexacolpate (sometimes octocolpate). The exine stratification in all taxa studied is similar and characterized by unbranched columellae and a continuous, granular endexine. Sexine ornamentation in the Nepetinae is bireticulate, microreticulate or perforate. In perforate and microreticulate pattern a tendency towards a bireticulum could be recognized due to trace of secondary tectal connections. The bireticulate pattern is most common with variations of primary muri and secondary reticulum. In Hymenocrater and Schizonepeta the observed variation of sexine ornamentation is particularly valuable at the generic level. Pollen data support Lophanthus and Nepeta as very closely allied and Lallemantia is clearly distinct from Dracocephalum. The formerly suggested infrageneric relationships within Dracocephalum and Nepeta are only partly corroborated by palynological characters. Orbicules are absent in the Nepetinae.     

中国槲寄生属花粉形态的研究

首次系统地报道中国槲寄生属10种植物花粉形态。通过光学显微镜和扫描电镜观察,国产槲寄生属种类可按花粉的外壁纹饰分为两大类群,与形态上划分相一致。类群Ⅰ(8种)具不显著或近光滑的外壁纹饰,这一类型又可分为2个亚型:纹饰在花粉各个部位基本上是一致的和纹饰在赤道和极、沟两侧不一致的;类群Ⅱ(2种)外壁具显著的杆状纹饰。但花粉性状对形态上相近的种类鉴定意义不大。还讨论了槲寄生属花粉的可能的演化趋势。     

中国桑寄生科的孢粉学研究

系统报道了中国桑寄生科Loranthaceae33种5变种植物的花粉形态,并与澳大利亚2属6种植物的花粉形态做了比较。通过光学显微镜和扫描电镜观察,国产桑寄生科花粉外壁纹饰可明显分为两个类型:一种类型为刺状或条状纹饰,另一种为颗粒状纹饰,这与该科的鞘花族和桑寄生族两个族相吻合。在鞘花族类型中,3合沟、钝刺状或条状纹饰的花粉是基本类型,合半沟或孔沟形,刺状纹饰的花粉是较进化的类型;在桑寄生族类型中,等极、3合沟、颗粒状纹饰的花粉是基本类型,异极、副合半沟-合半沟、3沟形和沟形-短沟形或沟孔形、粗糙或模糊颗粒状纹饰的花粉是较进化类型。根据萌发孔和纹饰可将桑寄生族类型花粉分为3个类群:类群I包括五蕊寄生属Dendrophtho、梨果寄生属Scurrula、钝果寄生属Taxillus和大苞寄生属Tolypanthus;类群II仅包括离瓣寄生属Helixanthera;类群III也仅1属,桑寄生属Loranthus。在这3个类群中,类群I属于基本的类型,属间花粉差别较小,其中梨果寄生属和钝果寄生属花粉差别最小,显示出较近的亲缘关系;类群II和类群III皆是较进化类型。     

Pollen wall stratification and pollination

Qualities of the stratified pollen walls were evaluated for their possible role in pollination (pollination modes, and pollen tube formation). The importance of studying pollen grains in their respective natural state is noted. Examples of pollen morphological features specific to pollination vectors are rare and difficult to demonstrate. However, some complex, but significant correlations are reported.     

Comparative pollen morphology of Glechoma and Marmoritis(Nepetinae,Lamiaceae)

The pollen morphology of 13 taxa(34 specimens)of the genera Glechoma L.,and Marmoritis Benth.was investigated in detail using light,scanning electron,and transmission electron microscopy.Pollen grains of all studied taxa are small to large in size(P = 32.5-60.4μm,E = 20.2-50.5μm),prolate-spheroidal to prolate in shape and mostly hexacolpate(the amb more or less circular or rarely ellipsoid)with granular membranes.The sexine ornamentation of Glechoma is bireticulate; the muri of the primary reticulum are irregularly circled,and lumen size is short.In contrast,the sexine surfaces of the Marmoritis pollen tend to more elongate or wider at the muri of the primary reticulum than those of the Glechoma.The pollen wall stratification of selected taxa(three from Glechoma and one from Marmoritis)is characterized by unbranched columellae,and continuous or distinctly discontinuous endexine based on transmission electron microscopy observation.The results of Glechoma and Marmoritis reveal rather similar pollen morphological features,however,fine details of sexine ornamentation are characteristic to differentiate the pollen taxa.Although these differences may be useful in establishing the taxonomic boundary between two genera,they are too weak to segregate diagnostic characters.     

樱属花粉形态研究

本文对樱属(Cerasus)9个种和变种的花粉形态进行光学显微镜观察,并结合电镜观察结果进行初步比较。结果表明,樱属花粉的极面观为圆形或近三裂圆形,赤道面观为椭圆形,三孔沟,外壁纹饰多为条纹状。属内特征基本一致,但种间存在着花粉大小、外壁纹饰的细微差别。     

华中铁角蕨孢子纹饰形成的超微结构观察

利用透射电子显微镜对铁角蕨科（Aspleniaceae）华中铁角蕨(Asplenium sarelii Hook.)孢子及其纹饰的形成过程进行观察。结果表明：①华中铁角蕨孢子囊发育为薄囊蕨型;②孢子外壁表面光滑;远极面的外壁厚约0.8～1.1 μm;近极面的外壁厚约1.4～1.8 μm;③孢子周壁厚度约4～5 μm;染色较外壁深;分为内层和外层;内层紧帖外壁表面;其上具柱状、瘤状或疣状突起;外层向外隆起形成脊状纹饰的轮廓;脊的下方具空腔;脊的顶端具翅;④铁角蕨型与鳞毛蕨型孢子外壁和周壁纹饰的形成过程具有相似性;⑤孢子的成熟度对于孢子形态的研究是至关重要的;只有完全成熟的孢子的表面纹饰才是稳定的。     

Pollen morphology within the Monodora clade,a diverse group of five African Annonaceae genera

Pollen morphology has played a major role in elucidating infrafamiliar‐level systematics and evolution within Annonaceae, especially within the African genera. The Monodora clade is composed of five genera, Asteranthe, Hexalobus, Isolona, Monodora and Uvariastrum, which are restricted to Africa and contain together c. 50 species. A molecular phylogeny of the family showed that the monophyly of the Monodora clade is strongly supported and that it is part of a larger clade of 11 African genera. In order to support classification a detailed survey was made of the pollen morphological variation within the Monodora clade, using scanning and transmission electron microsopy. For the two most species‐rich genera, Isolona and Monodora, a molecular species‐level phylogeny was used to assess the taxonomic usefulness of the pollen characters. The survey showed a wide range of pollen morphological diversity. The most conspicuous variation concerned the occurrence of monads without a thicker outer foliation in the basal exine layer in Isolona in contrast to tetrads with a thicker outer foliation in Asteranthe, Hexalobus, Monodora and Uvariastrum. At the infrageneric level, Hexalobus, Isolona and Monodora showed the largest diversity, with various pollen types based on tectum morphology. Hexalobus is exceptional with three types within only five species. The pollen types defined in this study are hardly useful in characterizing major groups identified within both Isolona and Monodora, but they do illustrate relationships within smaller groups.     

不同品种烟草花粉电子显微镜观察

通过对10个烤烟品种、8个晒烟品种、2个野生种的花粉进行扫描电子显微镜观察,发现同为烤烟或晒烟的烟草,其花粉的形态、大小、外壁纹饰比较稳定。野生烟在供试种中具有独特的细网状外壁纹饰,是鉴别野生烟与非野生烟的一条有效途径。     

Pollen productivity variations. Pollen-ovule ratio and sexual selection in Pinus roxburghii

Total pollen production, pollen-ovule ratio and the production of male-female strobili were recorded in Pinus roxburghii at two different altitudes during two successive years. The values of total pollen production per tree and per hectare varied between 1953.56 to 2727.16 2 10 9 and 2.91 to 4.26 2 10 14 (in 1999) at the lower altitude and 1247.5 to 1673.5 2 10 9 and 2.24 2 10 14 (in 1998) and 1599.89 to 2038.96 2 10 9 and 3.18 2 10 14 (in 1999) at the higher altitude. The pollen-ovule ratio in P. roxburghii has indicated the xenogamous type of breeding system The production of male and female cones per tree and per hectare ranged from 21.7 - 0.34 to 33.6 - 0.71 2 10 3 and 55.16 - 24.08 to 220.85 - 87.75 per tree and 32.55 to 70.56 2 10 5 and 2.76 to 26.50 2 10 3 per hectare respectively. However the production of female cones per 100 male cones oscillated between 0.25 to 0.66, which suggested the intense male competition among trees to pollinate their neighbours. A linear correlation was recorded between diameter and extent of the tree crown to the total production of strobili groups/strobili clusters, strobili, microsporophylls and pollen grains per individual tree. The ratio between the number of strobili per strobili group and the number of strobili groups per tree showed an inverse relationship; thus, the individuals with most strobili groups have the strobili groups with the least strobili and vice-versa. This ratio was also shown between the number of pollen grains per strobilus and the number of strobili per tree, as well as the number of pollen grains per strobili group and the number of strobili groups per tree.     

A glance into the vegetation and settlement of the fortress islands of Suomenlinna,Helsinki.: Pollen analytical study

Pollen studies were carried out of the sediments from a small pond on Susisaari, the largest island of the fortress of Suomenlinna, Helsinki. Three cores with altogether 80 samples were analysed, but only one core being reported here and additional comments are given on the results from two other cores. As it is most probable that the material has been mixed in several constructional phases during the last 100-200 years, the results were interpreted as one unit representing aerial and local vegetation during approximately that period. The results were compared with the recent vegetation, with the history of imported species, and with three botanical inventories made on the islands during the 20th century. Differences in pollen production and in pollen dispersal properties of different species strongly affect the results.     

中国沙拐枣属植物花粉形态及其在地层研究中的意义

通过光学显微镜和扫描电镜观察了中国沙拐枣属(Calligonum L.)11种植物的花粉形态。按扫描电镜下的外壁纹饰分类,该属花粉可分为4种类型,即:网纹-穴状具圆形或近圆形网眼、网纹-穴状具多角型网眼、网纹-穿孔和网纹-穿孔或小沟渠。它们的演化趋势是从前面类型依次向后面类型演化。根据花粉内孔的形状,沙拐枣属植物花粉可区别于蓼科其它属植物三孔沟类型花粉。     

Ultrastructure and diversity of recent and fossil zona-aperturate pollen grains

A survey of recent and fossil zona-aperturate pollen grains within the angiosperms was undertaken. Zona-aperturate pollen (with complete ring-like apertures) has been evolved independently in several genera of basal angiosperm families (Nymphaeaceae, Eupomatiaceae, Annonaceae, Monimiaceae, Atherospermataceae) and monocots (Araceae, Iridaceae, Laxmanniaceae, Arecaceae, and Rapateaceae). The special case of the eudicot Limnanthes (Limnanthaceae) is discussed. New examples of recent and fossil fully zonate pollen are presented; a noteworthy new example are Scrophulariaceae, with Pedicularis; our fossil examples show affinities either to Nymphaeaceae, or Araceae, or Iridaceae, or cannot be related to an extant taxon. The zona-aperturate pollen grains differ in ornamentation and stratification mostly in the respect of the aperture areas, but sometimes also outside the aperture. The question of polarity is settled only for some taxa because of the frequent lack of tetrad observations. A ring-like aperture may divide the pollen grains in symmetric halves, or if running asymmetrically, divides the pollen grain in two more or less unequal halves; the presence of clearly unequal halves gives a strong argument to assume an equatorial ring in such cases where tetrad configurations were not available. The zona-aperturate condition may be a functional benefit in wet environments: while in dry pollen the apertural ring is completely closed, in wet or very moist realm it expands greatly, and the pollen tube can be formed quickly and everywhere in this area.     

A Motor-Controlled Device for Slow-Motion Cutting with the Ultramicrotome

The preparation of ultrathin sections of high quality with a Porter-Blum microtome requires that the drive wheel be rotated at a slow, uniform rate during actual cutting. A mechanical device to control the motion of the microtome drive wheel consists of a synchronous motor connected to a drive shaft (4 rev/min), which can be intermittently coupled to the rim of the microtome wheel by a friction drive of 1/2-inch diameter. The microtome drive wheel is rotated manually at a rapid rate until the specimen is about to come into contact with the knife; then the mechanical drive is engaged for slow movement during cutting. When the section has been cut, the drive is disengaged by a lever operated with the left hand; after which, the microtome wheel is turned quickly back to the cutting position with the right hand.