排序方式： 共有18条查询结果，搜索用时 328 毫秒
1.
The Xizang (Tibetan) flora with numerous endemics is of importance in Chi-
nese flora. According to recent statistics there are in Xizang 27 genera of spermatophytes
endemic to China, being only 2.25% percent of the total number of genera in the Xizang flora.
Four of them are regarded as palaeoendemics (14.81%) and the others as neoendemics (85.19%).
These endemic genera, of 30 species and 3 varieties, belong to 17 families, of which, Umbelli-
ferae contains 6 genera, 7 species and 3 varieties; Compositae has 6 genera and 7 species, and
Gentianaceae 1 genus and 2 species. All the other families each comprises one genus with a
single species.
The cosmopolitan families together comprising 14 genera with 15 species have the highest
perecentage (52.92%) and the tropical ones (5 families, 5 genera with 5 species) come to the next
(29.42%), followed by the temperate ones (3 families, 10 genera with 10 species) (17.66%). It
shows that these endemic genera are obviously related to the tropical flora and temperate one
in essence.
According to the number of species, the genera endemic to China and occurring in Xi-
zang flora may be grouped as fallows.
Monotypic endemic ones 14 (51.85%)
Ditypic endemic ones 6 (22.22%)
Oligotypic endemic ones 4 (14.81%)
Small endemic ones 3 (11.11%)
The formation of the endemic genera is correlated with the topography, climate and en-
vironmental conditions, and they may have resulted from the diversification in geography and
climatic influence for a long time. The southeastern part of Xizang Plateau is of very diverse
ecological conditions, with the adequate precipitation, which may explain the concentration of
these endemic genera in this region.
The largest similarity coefficient (38.30%) of the genera endemic to China and occurring
in Xizang is with those in Qinghai Plateau, next, with those in Yunnan and in Sichuan pro-
vinces (both 27.60%), which shows that these endemic genera are related to the floras of the
regions mentioned above.
The difference in the horizontal distribution of these endemic genera is obviously between
the southern and northern parts of Xizang Plateau. The vertical distribution of the genera is
also rather obvious, from 800 m to 5200 m above sea level, but concentrated in the zone of 3000
m to 4500 mm. Therefore their occurrence in Xizang is not only affected by the historical
environmental conditions but also controlled by the horizontal and vertical distribution.
The origin and evolution of some endemic genera, such as Psammosilene, Parateropyrum,
Sphaerotylos, Salweenia, Ajaniopsis, Xizangia, Sinoleontopodium, are discussed in this paper.
Parateropyrum, a monotypic palaeotropic endemic, belongs to the tribe Atraphaxideae in-
cluding Atraphaxis, Calligonum and Pteropyrum. It may be a comparatively advanced group
in the tribe, and is closely related to the genus Pteropyrum which is distributed in western
Asia. The genus Parapteropyrum has possibly survived as a palaetropic-tertiary relic in this
region.
Sphaerotylos, a member of the subtribe Sphaerotylinae, the tribe Boehmerieae in the family
Urticaceae, is a comparatively primitive genus in the tribe Boehmerieae so far known. As the
other subtribes, such as Boehmerinae, Sarconchlamydinae, Orecnidinae and Maoutinae, are dis-
tributed in the tropics, rarely in the subtropics, the genus is no doubt a palaetropic -tertiary
relic.
Sinoleontopodium, belonging to the tribe lnuleae in Compositae, is also related to the ge-
nus Leontopodium. It is probable that the genus Sinoleontopodium arised later than the other.
We come to the conclusion that the southern part of Xizang Plateau is also one of thecentres of the origin and differentiation of genera endemic to China. 相似文献
2.
赵永忠 《蒙自师范高等专科学校学报》2010,(6):50-54
从1955年初到1958年9月,云南分批在边疆部分民族地区实行了和平协商土地改革。从改革一开始,就受到了中央的高度重视,以谈话、会议发言、会议纪要等多种方式对四川少数民族地区和西藏的土地改革产生影响。具体说来,云南和平协商土地改革对川、藏地区和平协商土地改革的影响主要表现在两方面:一是四川少数民族地区、西藏虽然在土地改革前后发生了叛乱,但总体上还是保持了和平协商的方式,甚至四川的做法比云南的还要缓和。二是从内容上来看,主要都是对多余的土地实行没收或者征收、征购,其它生产、生活资料进行保护。 相似文献
3.
4.
5.
6.
7.
姚淦 《中国科学院研究生院学报》1992,30(2):179-180
A new species and a new record for China of the genus Adoxa L.are reported from Xizang, China. They are Adoxa xizangensis G.Yao and Adoxa inodora (Falc.ex C.B.Clarke) Nepomn. 相似文献
8.
竞生香青Anaphalis yangii Y. L. Chen&Y. L. Lin外形近似灰叶香青A. spodiophylla Ling&Y. L. Chen，主要的区别是叶较厚，宽椭圆形或近圆形，两面被淡黄灰色绵毛，中脉在背面明显突起，头状花序少数密集成宽1. 5-3cm的复伞房花序，总花序梗常不分枝。 相似文献
9.
The present paper is the Supplement 2 to the Flora of Xizang, based upon
a collection in 1980 by Mr. W. L. Chen et al. from Mêdog, the south-eastern part of
Xizang. In the paper 11 new species are desribed and 10 new-record species are repor-
ted. All the type specimens are kept in the Herbarium of the Institure of Botany,
Academia Sinica (PE). 相似文献
10.
西藏缓步动物两新记录种记述 总被引：2，自引：0，他引：2
记述了西藏2个缓步动物新纪录,它们是哈氏大生熊虫和胡氏大生熊虫。这2个种同属于缓步动物门(Tardigrada)、真缓步纲(Eutardigrada)、并爪目(Parachela)、大生熊虫科(Macrobiotidae)、大生熊虫属(Macrobiotus)。 相似文献