Leaf micromorphology inAgathis and its taxonomic implications

This study surveys the micromorphological surface structure of the leaves of the conifer genusAgathis (Araucariaceae) from throughout the range of the genus (Malaysia to New Zealand and Fiji) as seen with the scanning electron microscope. These data confirm that the vegetative parts ofAgathis are taxonomically highly conservative, but suggest the Melanesian and New Zealand elements to be distinctive from those of the rest of the genus, and from one another. Conclusions are compared with those that have been derived from studies based on other characters.     

An Estimation Procedure for the Joint Distribution of Spatial Direction and Thickness of Flat Bodies Using Vertical Sections. Part II: An application in soil micromorphology

In soil micromorphology fissures are considered in vertical sections. To get information about the properties of the soil the joint distribution of spatial direction and width of these fissures is of interest. The fissures are mathematically generalized to flat bodies which are defined as stationary weighted surface processes with the weight “thickness”. In a typical point of the surface process suitable, joint parametric distributions of direction and thickness are assumed. The parameters have to be estimated from measurements on vertical sections which are taken from the soil. On these sections only a visible thickness and a visible angle can be observed. The joint distribution of these variables can be expressed by the joint distribution of spatial direction and thickness with the same parameters and in this indirect way the parameters can be estimated. The paper describes how to randomize the vertical section and how to measure the visible variables on the sections. The Chi-Square method is proposed for the parameter estimation. Further it is discussed how to derive good starting values for the numerical procedure. All this is demonstrated in a simulation study using the Bingham-Mardia distribution for the direction and the lognormal distribution for the thickness including a way to correlate the mean thickness and the direction. Finally an application in soil micromorphology is demonstrated for one soil horizon.     

A new pollen type,C-banded and fluorochrome counterstained chromosomes,and evolution inGuatteria and related genera (Annonaceae)

Guatteria, Guatteriopsis, Guatteriella andHeteropetalum share the same conspicuous pollen type which is new for theSpermatophyta. It is zonoaperturate with a folded aperture region and an extremely reduced exine. First chromosome counts and karyotype analyses forGuatteriopsis (4 species investigated) andGuatteriella (1 species) are identical with those ofGuatteria (19 species seen): 2n = 28. The genome is characterized by diploidization and partly telocentric chromosomes. Sequentially Giemsa C- and fluorochrome banded chromosomes and interphase nuclei are described. The cuticular folding pattern is distinct forHeteropetalum only. Growth forms and ecology are reported for many species. The evolutionary pattern of theGuatteria group is discussed and compared with other genera and families.     

The effect of endogenous and externally supplied nitrate on nitrate uptake and reduction in sugarbeet seedlings

The pericarp of the dormant sugarbeet fruit acts as a storage reservoir for nitrate, ammonium and -amino-N. These N-reserves enable an autonomous development of the seedling for 8–10 d after imbibition. The nitrate content of the seed (1% of the whole fruit) probably induces nitrate-reductase activity in the embryo enclosed in the pericarp. Nitrate that leaks out of the pericarp is reabsorbed by the emerging radicle. Seedlings germinated from seeds (pericarp was removed) without external N-supply are able to take up nitrate immediately upon exposure via a low-capacity uptake system (v_max = 0.8 mol NO ₃ ^- ·(g root FW)^–1·h^–1; K_s = 0.12 mM). We assume that this uptake system is induced by the seed nitrate (10 nmol/seed) during germination. Induction of a high-capacity nitrate-uptake system (v_max = 3.4 mol NO ₃ ^- ·(g root FW)^–1·h^–1; K_s = 0.08 mM) by externally supplied nitrate occurs after a 20-min lag and requires protein synthesis. Seedlings germinated from whole fruits absorb nitrate via a highcapacity uptake mechanism induced by the pericarp nitrate (748 nmol/pericarp) during germination. The uptake rates of the high-capacity system depend only on the actual nitrate concentration of the uptake medium and not on prior nitrate pretreatments. Nitrate deprivation results in a decline of the nitrate-uptake capacity (t_1/2 of v_max = 5 d) probably caused by the decay of carrier molecules. Small differences in K_s but significant differences in v_max indicate that the low- and high-capacity nitrate-uptake systems differ only in the number of identical carrier molecules.Abbreviations NR nitrate reductase - pFPA para-fluorophenylalanine This work was supported by a grant from Bundesministerium für Forschung und Technologie and by Kleinwanzlebener Saatzucht AG, Einbeck.     

华北地区莴苣属（广义）植物花粉特征的研究

本文研究了华北地区莴苣属（广义）７种植物的花粉形态与微形态特征。结果表明：莴苣属（广义）内这些种具有相同的花粉类型。该属的花粉为球形,３孔沟;极面观为三裂圆形,近六边形;赤道面观为圆形;花粉表面具网状纹饰,同胞１５个,网脊上有许多小穴和规则排列的刺。与邻近属形成明显差异,使该属成为一个自然类群。新属毛鳞菊属ＣｈａｅｔｏｓｅｒｉｓＳｈｉｈｇｅｎ．ｎｏｖ．以其花粉网状纹饰的网脊上具不规则排列的短柱而有别于莴苣属（广义）。花粉的形态特征与微形态特征可为菊科属级水平分类提供重要依据。     

Pericarp structure and phylogeny of theLamiaceae-Verbenaceae-complex

Pericarp structure was investigated in 158 species of the familiesLamiaceae andVerbenaceae. Data from 221 out of 262 genera ofLamiaceae s.l. and a few ofVerbenaceae s.str. were collected in a table. A cladistic analysis was performed on the basis of pericarp characters only. The abandonment of subfam.Pogostemonoideae as a taxonomic unit is considered. Examples of groups given additional support by similarities in pericarp characters are: (1) the gynobasic-styled labiates (subfamiliesPogostemonoideae, Lamioideae, Nepetoideae); (2) aLamioideae-Pogostemonoideae-group; (3)Nepetoideae; (4) aWestringia-Hemigenia-Hemiandra-Microcorys group (in subfam.Chloranthoideae); (5) aLepechinia-Chaunostoma-group (inNepetoideae); (6) aPrunella-Cleonia-group (inNepetoideae).     

绿绒蒿属一中国新记录种——尼东绿绒蒿

中国西藏植物多样性较为丰富,尽管已经进行了多次的植物多样性调查,但仍存在较严重的不均衡现象,部分地区和类群存在采集不足,甚至空白。我们针对西藏日喀则植物多样性调查薄弱区域开展调查,发现一个未记录的绿绒蒿属(Meconopsis Viguier)植物,采集了标本和种子。经查阅《西藏植物志》《中国植物志》、Flora of China、Flora of Nepal鉴定为尼东绿绒蒿(M. dhwojii G. Taylor ex Hay)。该文植物新资料报道如下:(1)尼东绿绒蒿形态描述及其彩色图片。(2)该植物种子微形态、与近似种间的形态差异。新发现丰富了中国绿绒蒿属植物多样性,对研究西藏乃至中国绿绒蒿属植物具有一定的生物地理学意义和潜在的园艺价值。绿绒蒿属分类须加强野外调研,多技术手段开展研究。     

Lemma micromorphological characters in the Chloridoideae (Poaceae) optimized on a molecular phylogeny

Eight lemma micromorphological characters of 83 taxa representing 61 genera in the Chloridoideae have been investigated using Scanning Electron Microscopy, including long cells, cork cells, stomata, bicellular microhairs, papillae, silica cells, microprickles, and macrohairs. Five new types of lemma micromorphological characters were reported here. Data for 27 taxa representing 19 genera from previous publications were also supplied to access the homology of lemma micromorphological characters for different groups through optimization onto a molecular cladogram. Given the optimization, five characters including long cells, cork cells, stomata, papillae, microprickles are of phylogenetic significance for supra-generic groups. Seven characters including straight outline long cells, crescent-shaped cork cells, absent stomata, absent papillae, dumb-bell-shaped silica cells, c-type microprickles, and papillate-base macrohairs may not be homologous, however, the enneapogonoid-type bicellular microhairs appeared as a synapomorphy for the Chloridoideae.     

蜘蛛抱蛋属植物叶表皮微形态的扫描电镜观察

在扫描电子显微镜下,观察9种蜘蛛抱蛋属植物的叶表皮微形态。结果表明,9种植物叶下表皮的细胞都为长方形,垂直壁为直的,垂周界限为凸的,外层周壁凹陷。气孔椭圆形至卵圆形,气孔外拱盖表面多平滑,其内缘近平滑、浅波状或锯齿波状;角质膜多为脊状条纹、有的外层周壁有横纹或颗粒。气孔大小与染色体的倍性有一定的正相关关系。不同种间叶表皮特征表现出一定差异,对种的划分有一定的分类鉴定意义。