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大头茶族的范围及族内属的界限 总被引:3,自引:0,他引:3
广义大头茶族几乎包括了整个山茶亚科的属,分群的界限不够明确,易于造成混乱,经过研究,作者所持的是狭义大头茶族的概念。考察这一族包括Polyspora, Gordonia和Laplacea三个属形态特征上的差异和洲际分布的事实,这三个属虽然有共同的祖先,但由于演化上的歧异,仍应作为独立的属看待。在划分属的界限上,苞被分化与否和花部其他形态的差异具有最重要的意义,花粉表面纹饰的差异也可作为一种依据。Polyspora种群划分也被讨论。 相似文献
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Tsou CH 《American journal of botany》1998,85(11):1531-1547
The early floral development of Camellioideae was studied. Two major evolutionary lineages were recognized for this subfamily. The earlier evolved lineage (Camellia, Polyspora, and Pyrenaria) has normally 11-14 perianth members, which are initiated in a continuous spiral and are differentiated into sepals and petals at late floral development, and numerous stamens initiated individually and centrifugally on the whole androecial region. The later derived lineage (Franklinia, Hartia, Schima, and Stewartia) has five sepals and five petals arranged in two whorls, and numerous individual stamens originating centrifugally from the five petal-opposed zones. Hartia-Stewartia and Franklinia-Schima further diverged as two branches - the former is characterized by having androecial fascicles and axile-basal placentation. The androecial fascicle is considered to be derived within this subfamily. The latter exhibits a higher degree of carpellary congenital fusion and axile-central placentaion, and as a whole, is concluded to be the most advanced group in the Camellioideae. A taxonomic treatment of the Camellioideae at the tribal level is also proposed. 相似文献
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