海南省粗叶木属新记录植物五种

报道发现于海南省鹦哥岭的粗叶木属(Lasianthus Jack)海南省新记录种5种,并描述了它们的主要辨认特征。其中4种(华南粗叶木Lasianthus austrosinensis H.S.Lo、长梗粗叶木L.filipes Chun ex H.S.Lo、西南粗叶木L.henryi Hutch.、台湾粗叶木L.formosensis Matsum.)在与海南邻近的广东省与广西壮族自治区均有记录,而大叶粗叶木L.rigidus Miq.则在热带亚洲具有明显的间断性分布。     

The Effect of the Apical Bud on the Growth of Lateral Buds on Subterranean Shoots

The influence of the apical bud on the growth of the lateral buds on subterranean shoots was studied in Stachys sieboldiiMig. and Helianthus rigidus(Gass.) Desv. Removing and damaging the apical parts of subterranean shoots or their treatment with 2% chlorocholine chloride shoot enhanced shoot branching. The response to light of the apical bud was invariably negative: the stolons, which came out or were extracted from the soil, grew back into the ground (negative phototropism). The response to light of lateral buds was autonomous and depended on the conditions of their initiation. The lateral buds developed in darkness manifested negative phototropism when withdrawn from the soil and exposed to the light, whereas the buds developed in the light showed positive phototropism. The author concludes that the concept of apical dominance, thoroughly studied in aboveground shoots, is also valid for subterranean shoots. However, in contrast to the former, in the latter case, the apical bud does not control the growth orientation of the lateral buds.     

Argentinian plant extracts with relaxant effect on the smooth muscle of the corpus cavernosum of Guinea pig

Extracts of different polarity from Baccharis trimera, Haplopappus rigidus Huperzia saururus, Maytenus ilicifolia, Satureja parvifolia and Senecio eriophyton were tested for their relaxant activity on smooth muscle using L-phenylephrine precontracted strips of corpus cavernosum obtained from Guinea pigs. Highly significant and dose dependent results were obtained with the dichloromethane extracts of H. saururus (87% of relaxation at the dose of 10 mg/ml), S. parvifolia (95% of relaxation at 2.5 mg/ml) and S. eriophyton (94% of relaxation at 5 mg/ml). Similar effects were observed with the methanol extracts of H. saururus (88% of relaxation at 10 mg/ml) and S. parvifolia (84% of relaxation at 10 mg/ml). These results were comparable to those obtained with the dichloromethane and methanol extracts of the well known Mexican species Turnera diffusa. Moreover, the aqueous extract of H. rigidus and the aqueous and methanol extracts of S. eriophyton were highly effective in a dose dependent manner (more than 90% of relaxation at the dose of 10 mg/ml). Significant results, but with a lower overall relaxant activity (about 70% of relaxation at 10 mg/ml), could also be obtained with the aqueous extract of S. parvifolia and with the dichlormethane and methanol extracts of B. trimera and M. ilicifolia. The positive controls with Sildenafil citrate at doses ranging from 0.35 to 35 microg/ml yielded moderate effects (up to 46% of relaxation at 35 microg/ml). The effects observed in the present study seem to validate the folk medicinal use of the tested plants and open new ways in the search for natural products with vasodilatory effects.     

Holcus azoricus M. Seq. & Castrov. (Poaceae), a new species from the Azores Islands

A new species of Holcus L. (Poaceae), endemic to the Azores archipelago (Portugal), is described. The vegetative and reproductive structures were studied. The diagnostic characters were compared with those of closely related species. New chromosome counts in Holcus azoricus M. Seq. & Castrov. (2 n  = 35) and H. rigidus Hochst. (2 n  = 28) are included. A possible hybrid origin is hypothesized; the potential parents are H. lanatus L. and H. rigidus .  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 259–267.