越南赤车属(荨麻科)二新记录

报道越南赤车属(荨麻科)二新记录种,即翅茎赤车(Pellionia caulialata S．Y．Liou)和光果赤车(P ．leio-carpa W．T．Wang),并提供描述.它们原记载分布于中国,现在越南北部发现有分布,凭证标本保存在PE.     

New Taxa of Salix L. from West China

Two new species and one new variety of Salix L. from western China, namcl. S. ludingensis T. Y. Ding et C. F. Fang, S. neoamnematchinensis T. Y. Ding et C. F. Fang, and S. taoensis Gorz var. leiocarpa T. Y. Ding et C. F.Fang, are reported in this paper.     

Structure of Anogeissus leiocarpa Guill., Perr. natural stands in relation to anthropogenic pressure within Wari‐Maro Forest Reserve in Benin

The present study focused on the analysis of the structure of the Anogeissus leiocarpa dominated natural stands in the Wari‐Maro forest reserve which are under high and minimal anthropogenic pressures. These stands were considered for forest inventories after carrying out a random sampling scheme of 40 sample units of 30 m × 50 m. In each level pressure stand, the dbh and tree‐height of identified tree‐species were measured in each plot. Data analyses were based on the computation of structural parameters, establishment of diameter and height distributions and the floristic composition of the two types of stands. Results obtained showed higher values for the overall basal area (9.78 m² ha^?1), mean height (22.37 m) and mean diameter (36.92 cm) for A. leiocarpa in low‐pressure stands. In high‐pressure stands, some species like Afzelia africana had lower Importance Value Index and the frequency of A. leiocarpa trees in the successive diameter classes dropped rapidly and the value of the logarithmic slope of the height–diameter relationship was lower (9.77) indicating a lanky shape. Results obtained suggest that effective conservation is needed for A. leiocarpa stands under high pressure by limiting human interference and developing appropriate strategy for restoration purposes.     

Carotenoids in petals of some perennial Medicago species

The petal carotenoids of several Medicago species, some of them considered as intermediate between the genera Medicago L. and Trigonella L. were investigated. Characteristics common to all species were: (a) the carotene fraction was small (0·2–4·4%) compared with the xanthophylls and their epoxy derivatives, (b) lutein, lutein-5,6-epoxide and violaxanthin constituted 83·7–98·1% of total content and thus were the prominent group in all species, (c) no single carotenoid of appreciable amount was characteristic to any species, (d) groups of related species tended to have similar quantities of major carotenoids.