SYSTEMATICS OF SOUTH AMERICAN TRIPSACUM (GRAMINEAE)

The genus Tripsacum is widely distributed between 42°N and 24°S latitude. In South America, the genus extends around the Amazon and Orinoco basin, and from the Caribbean coast south to Brazil and Paraguay. The most common South American taxon is T. dactyloides (L.) L. var. meridonale de Wet and Timothy (2n = 36), which differs from North American representatives of the species in having subdigitate recemes usually appressed with the apical male sections typically curved. Closely related to T. dactyloides, but usually occupying more seasonally moist and dry habitats, is T. australe Cutler and Anderson. This species is typically robust with the basal leaf sheaths tomentose, and the much elongated culms becoming decumbent in older plants. Smaller plants, with essentially erect culms and leaf sheaths on the culms hirsute rather than tomentose, are recognized as T. australe var. hirsutum de Wet and Timothy. The two varieties of T. australe are both diploid (2n = 36) and they cross to produce fertile hybrids. They also cross with T. dactyloides var. meridonale (2n = 36), but these hybrids are partially sterile. Tripsacum cundinamarce de Wet and Timothy (2n = 36) is a robust species with glaucus leaves. It resembles robust specimens of T. dactyloides in having glabrous leaf sheaths, but can always be recognized by inflorescences that are composed of racemes arranged along a several-noded primary axis. This species is confined to moist habitats, while T. dactyloides occupies a range of habitats in South America. Tripsacum peruvianum de Wet and Timothy is a gametophytic apomict with 2n = 72, 90 or 108 chromosomes. It is characterized by an erect growth habit and strongly hirsute leaf sheaths. The cultivated Guatemala grass, T. andersonii Gray, occurs spontaneously in the mountains of Venezuela, Colombia, and Peru. This sexually sterile species is characterized by 2n = 64, and may combine 54 Tripsacum and 10 Zea chromosomes in its genome. Electrophoretic patterns of seed storage proteins confirm the validity of recognizing T. cundinamarce as distinct from T. dactyloides, and T. peruvianum as distinct from T. australe.     

三种观赏植物的染色体研究

三种观赏植物的染色体研究黄少甫,赵治芬（中国林科院亚热带林业研究所,浙江富阳３１１４００）关键词翠菊,百日菊,溪荪,染色体,核型ＳＴＵＤＩＥＳＯＮＣＨＲＯＭＯＳＯＭＥＳＯＦＴＨＲＥＥＧＡＲＤＥＮＰＬＡＮＴＳ￥ＨｕａｎｇＳｈａｏｆｕａｎｄＺｈａｏＺｈｉ...     

巴基斯坦药用植物研究概况

我们曾于1996年10月回日至20日作为中国政府"援巴基斯坦药用植物中心考察项目"考察组成员赴巴基斯坦,就我国政府援建巴基斯坦药用植物中心进行可行性考察。现将巴基斯坦药用植物研究概况综述如下。1药用植物资源的研究巴基斯坦地形复杂多样,山区和丘陵约占全国总面积的3／5。     

STUDIES ON BIOLUMINESCENCE : XIV. THE SPECIFICITY OF LUCIFERIN AND LUCIFERASE.

Among sixteen groups of luminous forms investigated by the author, in only four (fireflies, Pholas, ostracods, and Odontosyllis) is it possible to demonstrate the luciferin-luciferase reaction. In many groups this is probably due to the small amount of these substances present in the luminescent organism or to their instability. In the medusæ and pennatulids, despite a large amount of luminescent material, luciferin and luciferase cannot be demonstrated. This does not appear to be due to the presence of luciferin and luciferase in equivalent proportion, or to their instability. In fact, one is led to the conclusion that luciferin and luciferase do not exist in these forms, but such a conclusion must be regarded as merely tentative, in view of the fundamental character of the luciferin-luciferase reaction. Luciferin of one form will not luminesce with the luciferase of another form or vice versa, unless very closely related (Cypridina and Pyrocypris). All experiments emphasize the specificity of the light producing substances of Cypridina.