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1.
胡玉熹 《中国科学院研究生院学报》1986,24(6):464-468
作者在扫描电镜下，比较观察了松属l7种2变种针叶角质层内表面的结构特征。结果
表明，针叶角质层内表面的角质颗粒突起与凹陷雕纹变化不甚明显，但胞间凸缘的特征差异较
为显著，如单维管束松亚属(白皮松组除外)为红松型，双维管束松亚属为油松型，而白皮松组
则为白皮松型。此一特征为松属的分类研究，又提供了一个新的证据。
本文综合讨论了松属针叶的结构及角质层内、外表面结构特征，木材解剖，木材管胞内壁
的瘤层特征，树皮显微结构，以及染色体组型分析等资料，作者认为：松属中两个亚属的划分是符合自然的，同时将原属单维管束松亚属中的白皮松组分出来，自成白皮松亚属也是合适的。 相似文献
2.
作者在光学显微镜及扫描电镜下，比较观察了三尖杉属Cephalotaxus 4种及1栽培变 种茎次生韧皮部的结构，主要结果为：(1)属内各种茎次生韧皮部的结构比较一致。横切面筛胞与薄壁组织细胞呈单层切向带交替排列; 厚壁组织切向带的径向宽为1—4个细胞，带间 距离较宽。(2)根据韧皮纤维的类型，石细胞数量多少或缺如，可作本属分种鉴定特征; 也为 属内分组提供了佐证。(3)本属茎次生韧皮部中有些薄壁组织细胞的内切向壁中嵌埋有草酸钙结晶。这有别于松柏类其它各科，也是自然分类的一新依据。 相似文献
3.
本文借助光学显微镜和扫描电镜，对豹子花属Nomocharis 6种植物和百合属Lilium 4
种植物的花粉形态与外部特征作了较系统的比较研究，其结果如下： 1．豹子花属植物花粉的
萌发孔均为单沟(远极)型，根据其外壁结构及表面纹饰的特点，可分为基柱网纹型和网纹
型，结合外部形态特征推断，可能存在由基柱网纹→网纹的进化趋势。 2．百合属植物花粉
的萌发孔多为单沟(远极)型，稀为2一3孔型，然而，其中外部形态极为相近的小百合集合群与
尖被百合在花粉形态上表现出较大的差异，这一事实为研究百合科花粉的演化提供了线索。豹
子花属与百合属花粉虽在表面纹饰上存在区别，但从外部形态上，该属的一些种类与百合属极 为相近，反映出二属之间存在着较为紧密的亲缘关系。 相似文献
4.
席以珍 《中国科学院研究生院学报》1986,24(4):247-252
红豆杉科(Taxaceae)，花粉近球形，有时稍扁或稍长。直径为20．8-45．8μm。具远极 薄壁区，或不典型的乳头状突起。外壁两层，内外层厚度相等，有时层次不明显。在光学显微 镜下，外壁表面粗糙，或具微弱的颗粒状纹饰。在穗花杉(Amentotaxus argotaenia)这个种里，有些花粉粒具残存气囊。在扫描电镜下，外壁表面具粗瘤和细瘤两种纹饰类型。透射电镜本科各属代表种观察表明，本科花粉外壁内层具片状结构，外层由单层瘤状纹饰分子构成，有 些种细瘤连接形成覆盖层。根据花粉形态资料，可将本科植物分为2个族： 白豆杉族(仅包括白豆杉一个属)和红豆杉族(包括红豆杉属和榧树属)。 鉴于穗花杉属花粉的特殊性，建议独立上升为穗花杉科Amentotaxaceae。 相似文献
5.
6.
调查色季拉山西坡方枝柏疏林不同海拔梯度的植物,研究物种组成、物种丰富度及重要值沿海拔梯度的变化。结果表明:(1)在调查的6个方枝柏疏林样地内,共有植物54种,分属于29科48属,其中乔木层2种分属2科2属,灌木层14种分属6科11属,草本层48种分属24科38属;(2)科数、属数、种数随海拔梯度变化均呈双峰曲线;(3)灌木层种数和海拔有显著的负相关性(P<0.05),草本层种数与总物种总数也有显著的相关性(P<0.05),而乔木层种数、草本层种数、总物种总数与海拔之间的相关性不显著(P>0.05);(4)随海拔的升高,乔木层树种的组成趋向单一化;灌木层在不同海拔带的方枝柏疏林内分别有明显不同的优势种;草本层在不同海拔高度中莎草科植物重要值最高,菊科植物重要值次之,其重要值均随海拔的升高呈下降趋势,草本层湿生植物与中湿生植物占绝对优势,方枝柏疏林群落表现出沼泽进程化趋势,方枝柏种群呈衰退型。 相似文献
7.
运用PCR方法分别从松科8属、9种植物中扩增出一长约2550bp的cpDNA片段，这一片段包括rbcL、trnR、部分accD及基因间的非编码区(相对于黑松cpDNA中的同源片段而言)。运用18种限制性内切酶对这一cpDNA片段进行酶切分析，共获得86个酶切位点，其中54个为变异位点。运用PAUP(version 3．1．1)和Mega(version 1．01)软件对数据进行分析，结果Wagner简约树和Neighbor-Joining树反映出的松科系统发育关系基本一致：银杉属、松属、黄杉属和落叶松属形成一个单系群，且银杉属与松属的亲缘关系更近于与另外二属的关系，但这一结果未得到Bootstrap分析的较强支持；落叶松属近缘于黄杉属；冷杉属近缘于油杉属。此外，松科中的冷杉亚科和落叶松亚科均不是单系类群，将松科划分为冷杉亚科、落叶松亚科和松亚科三个亚科的系统(郑万钧，傅立国，1978)是不自然的。 相似文献
8.
葡萄属植物花粉形态的研究 总被引：2，自引：0，他引：2
利用扫描电子显微镜对葡萄属Vitis L．37个类群(包括32种、1亚种和4变种)以及其近缘属麝香
葡萄属Muscadinia(Planch．)Small一种植物的花粉进行了观察,结果表明,葡萄属植物的花粉形态特征
在区别并鉴定属下的种类时有较大价值,但对种以上的分类以及研究系统演化无多大意义。葡萄属植
物的花粉形态特征可以分为4类：(1)花粉粒扁球形或圆球形(P/E值为O.97-1.08),沟较宽,可见被有
较密颗粒状突起的沟膜,属于该类的有紫葛V．coignetiae Pull．ex Planch．;(2)花粉粒长球形至近长圆球
形(P/E值为1.25～1.76),沟较宽,可见有较疏颗粒状突起的沟膜,该类型包括了庐山葡萄V．hui Cheng
等共10种1亚种3变种;(3)花粉粒长圆球形(P/E值为1.87～2.1),沟边缘紧靠合呈直线状,但在赤道
轴萌发孔处沟边缘分开呈菱形,该类型有秋葡萄V．romanetii Roman du Caill．ex Planch．和锈毛刺葡萄V．
davidii(Roman du Caill．)Foex．var．ferruginea Merr．et Chun等1种1变种;(4)花粉粒长球形或超长球形
(P/E值为1.30～2.0),沟边缘紧靠成直线状,麝香葡萄Muscadinia rotundifolia(Michx .)Small等21种的花粉属于此类型。 相似文献
9.
滇桐属(Craigia w.w.Smith ＆ W．E. Evans)植物的生殖器官与花粉的形态都比
较特殊,一直受到国内外学者的重视,究竟应将它归入梧桐科(sterculiaceae)还是椴树科
(Tiliaceae),长期以来都存在着不同的见解。为了帮助澄清这个问题,本文在过去研究中国
梧桐科花粉形态的基础上,从花粉形态的角度进行探讨,对滇桐属的花粉以及椴树科的椴属
(Tilia)、海南椴属(Hainania)、蚬木属(Excentrodendron)等4属16种花粉在扫描电子显微镜 和光学显微镜下进行观察。研究结果表明,滇桐属花粉与椴树科3个属的花粉在形状、极性、
萌发孔位置及其形状结构(包括孔室的形状)、表面纹饰等方面都有差异,但与梧桐科的苹婆
属(Sterculia)、梭罗树属(Reevesia)等的花粉形态比较接近,而且滇桐属的花的形态与苹婆属等的也很相似,因此我们认为把滇桐属置于梧桐科内是比较合适的。 相似文献
10.
本文对分布于我国的椴树科(Tiliaceae)9属44种植物的花粉形态进行了光学显微镜
的系统观察，并对其中10种花粉的外壁细微结构进行了扫描电镜观察。本科花粉为长球形、
扁球形和球形，萌发孔为长3孔沟、短3孔沟和3(一4)孔三种类型，外壁主要为网状纹饰，个 别属为刺状纹饰。根据花粉资料，本文还探讨了该科植物分类中的某些问题。 相似文献
11.
裘佩熹 《中国科学院研究生院学报》1974,12(2):237-248
As construed here the genus. Woodwardia Sm. does not include Anchistea Presl
and Lorinseria Presl of the east North America which are considered as distinct
genera nor Woodwardia harlandii Hook. and W. kempii Cop. of south china, which
constitute a new genus Chieniopteris Ching (cf. Acta Phytotax. Sinica 9:37. 1964).
It has been proposed that genus Woodwardia Sm. is an old one, dating back
perhaps from the early Tertiary in the Arctics, thence it spread to Europe, North
America, and southward to East Asia with its present center of distribution in China,
especially south of the Yangtze River.
The genus is now represented by 17 species in the Northern Hemisphere, of which
ll are known in China and her neighbouring countries, with one species, W. unigem-
mata (Makino) Nakai, ranging as far as the Himalayas, where from the previous re-
cord of W. radieans Linn. Sm. of Europe proves to be a mistake for this species.
The genus is divided into two natural series: Radicantes Ching & Chiu and Egem-
miferae Ching & Chiu, and the latter is further subdivied into 2 subseries: Orientales
Ching & Chiu and Japonicae Ching & Chiu.
A key to the Chinese species has been provided.
In passing it may be pointed out that Woodwardia cochin-chinensis Ching (Bull.
Fan Mem. Inst. Biol. 2: 7. 1931) is based upon Poilane nos. 2107 and 2275 without
designating the type. According to the International Code of Botanical Nomenclature
we herewith designate Poilanes no. 2275 the type of this species.
相似文献
12.
秦仁昌 《中国科学院研究生院学报》1964,9(1):99-99
The fern genus Diplaziopsis C. Chr. of Index Filicum has long been considered as
a monotypic one, with the sole species, D. javanica (B1.) C. Chr. from tropical Asia. In
1906, H. Christ described a second species, Allantodia cavaleriana Christ (=D. cavale-
riana C. Chr.) from Kweichow, West China, but this was since not fully recognized by
fern students in general, being often considered as a variety of the first species. This
is certainly a mistake, as is shown by ample herbarium specimens today. In the recent
work on the genus, the writer has found among the herbarium material two additional
new species from China, thus bringing the genus up to four species in Asia, mainly from
China, where, as it is, the genus has its center of development from the long past.
Phylogenetically, Diplaziopsis C. Chr. represents one of the offshoots from the great
stock of diplazioid ferns, of which the genus Diplazium Sw. constitutes the main body
of the group and from which our genus differs chiefly in its leaves of a thin texture with
reticulated venation, but not so much in its type of indusium as it has generally been
emphasized by most botanists in the past, for, as it is, the type of indusium in Di-
plaziopsis also prevails in many species of Diplazium, for which C. B. Clarke (Trans.
Linn. Soc. ser. 2, Bot. I:495, 1880) created, but really superfluously, a subgenus Pseudal-
lantodia, about which the writer will dwell in another paper in the near future. Suffice
it to say here that the indusium in Diplaziopsis as revealed by the species treated here
is, indeed, typical of diplazioid ferns, only often, as it happens, with its adaxial edge
pressed so tight under the expanding sorus that it is unable to open freely along its upper
free edge and, as a result, its thin vaulted back bursts open from the pressure of the ex-
panding sorus underneath.
As a result of the present study, following four species of the genus have been re-
cognized.
Diplaziopsis javanica (B1.) C. Chr. Ind. Fil. (1905) 227.
Wide spread in tropical Asia, northwardly to Bakbo and the southern part of Yun-
nan, China.
D. cavaleriana (Christ) C. Chr. Ind. Fil. Suppl. I (1913) 25.
Ranges from West China through northern part of Fukien of East China to Japan.
D. intermedia Ching, sp. nov.
Endemic in West China: Mt. Omei, Szechuan, and Kweichow.
D. hainanensis Ching, sp. nov.
In conclusion, it may be pointed out that with the modern plant taxonomy pursued
in a more efficient manner than in the past, and especially by the introduction of the
cytotaxonomic methods, the so-called “monotypic genera”, as conceived by the orthodox
systematists, will continue to prove, to a great extent, to be lack of enough scientific
ground. The fact that the “monotypic genus” of Diplaziopsis C. Chr. is now found to
be a genus of four well-defined species is once again an instance to illustrate the pointat issue. 相似文献
13.
通过光学显微镜和扫描电子显微镜对黄精族trib．Polygonateae 7属79种以及相关类群12属15种
的叶下表皮形态及种皮微形态进行了观察。结果表明广义黄精族植物的叶表皮形态和种皮形态可分别
分为4种类型和6种类型。在黄精族中,鹿药属Smilacina和黄精属Polygonatum的叶表皮和种皮特征在
属内表现出一定的多样性,据此可将黄精属植物分为两类：第一类多表现为叶表皮细胞形状不规则,其垂周壁为波曲形或无皱褶但弯曲,种皮表面浅穴状;另一类叶表皮细胞形状为长方形或菱形,其垂周壁
直或无皱褶但弯曲,种皮表面具脊状突起或网状结构。其中,叶表皮细胞垂周壁无皱褶但弯曲为过渡
类型,在两类植物中均有表现。本研究结果还显示出竹根七属Disporopsis和黄精属的互叶类以及鹿药属
同具有波状垂周壁的叶表皮细胞和穴型种皮。舞鹤草属Maianthemum和鹿药属的S．stellata,S．trifolia
等的种皮特征相似。万寿竹属Disporum的叶表皮特征在属内表现得相当一致,但种皮特征在东亚分布
的种和北美分布的种之间区别明显。扭柄花属Streptopus叶表皮和种皮特征在属内没有分化。卵叶扭
柄花S．ovalis的叶表皮和种皮特征与属内其它种之间没有区别,确证了它在本属中的位置。扭柄花属、
万寿竹属、七筋菇属Clintonia与黄精族其它类群差别较大,但前两者与Uvulariaceae科的油点草属Tricyr-
tis和细钟花属Uvudaria较为接近,从而支持了Dahlgren将其移至Uvulariaceae的观点。而在与外类群的关系中,铃兰族的铃兰属Convallaria与黄精族具相近的叶表皮和种皮特征。 相似文献
14.
首次全面论述了全世界黄华属(豆科)植物地理。黄华属是豆科少数几个东亚-北美间断分布属之一。对黄华属5组21种的分布进行了分析,发现本属4个频度分布中心依次是：东亚地区(8种／3组,其中特有种4种),伊朗-土兰地区(7种／3组,其中特有种3种),落基山地区(7种／2组,均为特有种)及大西洋北美地区(3种／1组,均为特有种)。基于以下事实：在东亚地区存在本属最多的组与种;在此区可以见到黄华属系统发育系列;该属最原始的组种及最进化的组种也在该区出现等,可以认为东亚地区是该属的现代分布中心及分化中心。伊朗-土兰地区(中亚东部至喜马拉雅)及落基山地区所含种、组数仅次于东亚地区,而且多倍体现象多发生于这两区,因此可认为是本属的次生分布中心及分化中心。在此二地区,物种分化较活跃且复杂,先后描述了很多新种和变种,也曾进行过较多的归并处理。最近的分子生物学证据不断揭示,在这地区曾被归并的一些分类群存在着较大不同,从而提醒分类学家对年轻区系中物种分化较活跃的类群进行分类处理时,无论是建新分类群还是对某些类群进行归并,应持谨慎态度。作者根据黄华属植物的现代地理分布、形态演化趋势、现有的化石及地质历史资料,推测黄华属植物在中新世之前早已形成,并且在晚第三纪欧亚大陆与北美大陆失去陆地连接之前在两大陆已经存在,很可能是于早第三纪或晚白垩纪在劳亚古陆上起源于一个含羽扇豆生物碱的古槐成员。两大陆分离后,在不同的成种因子的影响下,形成了各自的演化格局：在亚洲,晚第三纪的喜马拉雅造山运动、古地中海消失及第四纪冰川作用引起的旱化、寒化,促进了该属植物的强烈分化;而在北美,第四纪的冰川作用及局部的山体隆起,可能是促进该属植物演化的主要动力。根据黄华属植物的系统演化趋势及原始类群的分布式样分析,东亚地区的中国-日本亚区可能是本属植物的原始类型中心。 相似文献
15.
16.
论胡桃科植物的地理分布 总被引：1，自引：0，他引：1
路安民 《中国科学院研究生院学报》1982,20(3):257-274
The present paper aims to discuss the geog raphical distribution of the Juglandaceae
on the basis of unity of the phylogeny and the process of dispersal in the plants.
The paper is divided into the following three parts:
1. The systematic positions and the distribution patterns of nine living genera in
the family Juglandaceae (namely, Engelhardia, Oreomunnea, Alfaroa, Pterocarya, Cyclo-
carya, Juglans, Carya, Annamocarya and Platycarya) are briefly discussed. The evolu-
tional relationships between the different genera of the Juglandaceae are elucidated. The
fossil distribution and the geological date of the plant groups are reviewed. Through
the analysis for the geographical distribution of the Juglandaceous genera, the distribu-
tion patterns may be divided as follows:
A. The tropical distribution pattern
a. The genera of tropical Asia distribution: Engelhardia, Annamocarya.
b. The genera of tropical Central America distribution: Oreomunnea, Alfaroa.
B. The temperate distribution pattern
c. The genus of disjunct distribution between Western Asia and Eastern Asia:
Pterocarya.
d. The genus of disjunct distribution between Eurasia and America: Juglans.
e. The genus of disjunct distribution between Eastern Asia and North America:
Carya.
f. The genera whose distribution is confined to Eastern Asia: Cyclocarya, Platy-
carya.
2. The distribution of species
According to Takhtajan’s view point of phytochoria, the number of species in every
region are counted. It has shown clearily that the Eastern Asian Region and the Coti-
nental South-east Asian Region are most abundant in number of genera and species. Of
the 71 living species, 53 are regional endemic elements, namely 74.6% of the total species.
The author is of the opinion that most endemic species in Eurasia are of old endemic
nature and in America of new endimic nature. There are now 7 genera and 28 species
in China, whose south-western and central parts are most abundant in species, with Pro-
vince Yunnan being richest in genera and species.
3. Discussions of the distribution patterns of the Juglandaceae
A. The centre of floristic region
B. The centre of floristic regions is determined by the following two principles: a.
A large number of species concentrate in a district, namely the centre of the majority;
b. Species of a district can reflect the main stages of the systematic evolution of the
Juglandaceae, namely the centre of diversity. It has shown clearly that the southern
part of Eastern Asian region and the northern part of Continental South-east Asian
Region (i.c. Southern China and Northern Indo-China) are the main distribution centre
of the Juglandaceae, while the southern part of Sonora Region and Caribbean Region
(i.c. South-western U.S.A., Mexico and Central America) are the secondary distribution
centre.
As far as fossil records goes, it has shown that in Tertiary period the Juglanda-
ceae were widely distributed in northern Eurasia and North America, growing not only
in Europe and the Caucasus but also as far as in Greenland and Alaska. It may be
considered that the Juglandaceae might be originated from Laurasia. According to
the analysis of distribution pattern for living primitive genus, for example, Engelhar-
dia, South-western China and Northern Indo-China may be the birthplace of the most
primitive Juglandaceous plants. It also can be seen that the primitive genera and the
primitive sections of every genus in the Juglandaceae have mostly distributed in the
tropics or subtropics. At the same time, according to the analysis of morphological cha-
racters, such as naked buds in the primitive taxa of this family, it is considered that
this character has relationship with the living conditions of their ancestors. All the
evidence seems to show that the Juglandaceae are of forest origin in the tropical moun-
tains having seasonal drying period.
B. The time of the origin
The geological times of fossil records are analyzed. It is concluded that the origin
of the Juglandaceae dates back at least as early as the Cretaceous period.
C. The routes of despersal
After the emergence of the Juglandaceous plant on earth, it had first developed and
dispersed in Southern China and Indo-China. Under conditions of the stable tempera-
ture and humidity in North Hemisphere during the period of its origin and development,
the Juglandaceous plants had rapidly developed and distributed in Eurasia and dis-
persed to North America by two routes: Europe-Greenland-North America route and
Asia-Bering Land-bridge-North America route. From Central America it later reached
South America.
D. The formaation of the modern distribution pattern and reasons for this forma-
tion.
According to the fossil records, the formation of two disjunct areas was not due to
the origin of synchronous development, nor to the parallel evolution in the two con-
tinents of Eurasia and America, nor can it be interpreted as due to result of transmis-
sive function. The modern distribution pattern has developed as a result of the tectonic
movement and of the climatic change after the Tertiary period. Because of the con-
tinental drift, the Eurasian Continent was separated from the North American Conti-
nent, it had formed a disjunction between Eurasia and North America. Especially, under
the glaciation during the Late Tertiary and Quaternary Periods, the continents in Eu-
rasia and North America were covered by ice sheet with the exception of “plant refuges”, most plants in the area were destroyed, but the southern part of Eastern Asia
remained practically intact and most of the plants including the Juglandaceae were
preserved from destruction by ice and thence became a main centre of survival in the
North Hemisphere, likewise, there is another centre of survival in the same latitude in
North America and Central America.
E. Finally, the probable evolutionary relationships of the genera of the Juglanda-ceae is presented by the dendrogram in the text. 相似文献
17.
秦仁昌 《中国科学院研究生院学报》1964,9(1):37-40
A new fern genus, Chieniopteris Ching, based upon Woodwardia harlandii Hook.
from South China, is here proposed. Its systematic position seems to be apparently inter-
mediate between Lorinseria Presl of the east North America and Woodwardia Sm. of
the Old World, from the former the genus is distinguished by its upland habitat, by the
uniform fronds of chartaceous or rather subcoriaceous texture with straw-colored stipe
and rachis of the leaves; from the latter by the long creeping rhizome with distant
fronds, by the simple trilobed or generally simply pinnate lamina with a few pairs of
entire or sometimes irregularly lobated lateral pinnae, which are connected at the base
by a narrow wing on each side of the rachis, by the superficial and longer sori and by
the veins anastomosing between the sori and the leaf margin.
While describing the plant as a Woodwardia, Hooker properly noted that it is very
distinct from the oriental Woodwardia japonica (Linn. fil.) Sm. and W. prolifera Hook.
Later Baker transferred Hooker's species under Woodwardia sect. Lorinseria in Synopsis
Filicum in a juxtaposition with Woodwardia areolata (Linn.) Moore, the type of the
genus Lorinseria Presl. It is J. Smith, who referred the southern Chinese plant to Lorin-
seria Presl, with which it is somewhat similar in habit, but differs in characters diagnosed
above, besides a distinct habitat and geographic area.
The new genus is now represented by two species, C. harlandii (Hook.) Ching and
C. kempii (Cop.) Ching, all indigenous in South China, extending southwardly to the
northern part of Vietnam and eastwardly to the islands of southern Japan.
The new genus is named after professor S. S. Chien, director of the Institute of
Botany, Academia Sinica, and president of the Botanical Society of China, to celebratehis 80th. birthday last year. 相似文献
18.
方振富 《中国科学院研究生院学报》1987,25(4):307-313
1. The distribution of Salix species among the continents. There are about
526 species of Salix in the world, most of which are distributed in the Northern Hemisphere
with only a few species in the Southern Hemisphere. In Asia, there are about 375 species, mak-
ing up 71.29 percent of the total in the world, including 328 endemics; in Europe, about 114
species, 21.67 percent with 73 endemics; in North America, about 91 species, 17.3 percent with
71 endemics; in Africa, about 8 species, 1.5 percent, with 6 endemics. Only one species occurs
in South America. Asia, Europe and North America have 8 species in common (excluding 4
cultivated species). There are 34 common species between Asia and Europe, 14 both between
Europe and North America and between Asia and North America, 2 between Asia and Africa.
Acording to the Continental Drift Theory, the natural circumstances which promoted speciation
and protected newly originated and old species were created by the orogenic movement of the
Himalayas in the middle and late Tertiary. Besides, the air temperature was a little higher in
Asia than in Europe and North America (except its west part) and the dominant glaciers were
mountainous in Asia during the glacial epoch in the Quaternary Period. Then willows of Eu-
rope moved southwards to Asia. During the interglacial period they moved in opposite direc-
tion. Such a to-and-fro willow migration between Asia and Europe and between and North
America occurred so often that it resulted in the diversity of willow species in Asia. Those
species of willows common among the continents belong to the Arctic flora.
2. The multistaminal willows are of the primitive group in Salix. Asia has 28 species of
multistaminal willows, but Europe has only one which is also found in Asia. These 28 species
are divided into two groups, “northern type” and “southern type”, according to morphology of
the ovary. The boundary between the two forms in distribution is at 40°N. The multistami-
nal willows from south Asia, Africa and South America are very similar to each other and
may have mutually communicated between these continents in the Middle or Late Cretaceous
Period. The southern type willows in south Asia are similar to the North American multista-
minal willows but a few species. The Asian southern type willows spreaded all over the conti-
nents of Europe, Asia and North America through the communication between them before the
Quaternany Period. Nevertheless, it is possible that the willows growing in North America
immigranted through the middle America from South America. The Asian northern type mul-
tistaminal willows may have originated during the ice period.
The multistaminal willows are more closed to populars in features of sexual organs. They
are more primitive than the willows with 1-3 stamens and the most primitive ones in the ge-
nus.
3. The center of origin and development of willows Based on the above discussion it is re-
asonable to say that the region between 20°-40°N in East Asia is the center of the origin and
differentiation of multistaminal willows. It covers Southern and Southwestern China and nor-
thern Indo-China Pennisula. 相似文献
19.
李中明 《中国科学院研究生院学报》1983,21(2):153-160
The genus Palaeosmunda was established by R. E. Gould in 1970 based upon some
Late Permian Osmundaceous trunks with well-developed leaf gaps and rhomboidal
sclerotic ring within petiolar base seen in cross section. As he thinks that the latter
character is more important than the former, this genus could not be assigned to any
subfamily of Osmundaceae.
However, the leaf gap is one of the most important characters in the structure of the fern stem, so the author suggests that this genus should be assigned to subfamily
Osmundoideae and its diagnosis must be emended as follows:
The genus Palaeosmunda is represented by some rhizomes (or trunks), roots and
leaf bases of ferns which structurally are preserved, resembling Osmundacaulis but
which can’t be assigned to any group of this genus.
Stem containing an ectophloic dictyoxylic siphonostele; if tracheids present in
the pith, they being multiseriate scalariform pitted; pith or cortex sometimes contain-
ing groups of secretory cells or sclerenchyma; number of leaf traces seen in a tran-
sverse section of cortex more than 30; leaf traces adaxially curvature, rarely oblong-
shaped; petiolar bases with or without stipular expansion, containing a C-shaped
vascular strand; root diarch.
Type species——Palaeosmunda williamsii.
According to this diagnosis some primitive osmundaceous species with the leaf
gaps, which have already found in Upper Permian and Lower Triassic, could be assigned
to this genus. Two of them are P. williamsii Gould and P. playfordii Gould, and
Osmundacaulis beardmorensis, which was from Lower Triassic of Antarctica in 1978,
should be assigned to the genus Palaeosmunda.
In this paper two osmundaceous new species: P. primitiva and P. plenasioides were
found in the coal balls of Upper Permian age from Wangjiazhai of Shuicheng of
Guizhou Province, China.
P. primitiva is represented by two trunks; stem about 4 cm in diameter; stele
actophloic dictyoxylic siphonostele; pith cavity about 3—4 mm in diameter, contianing
parenchyma and tracheids; xylem cylinder thin, less than 10 tracheids in radial thick-
ness, dissected by leaf gaps. Inner cortex about 1.5 cm thick, mainly parenchymatous,
but sometimes containing a few sclerenchymatous; number of leaf traces seen in a
transverse section about 50—60; leaf traces departing at 35—45º,open C-shaped at
point of departure, gradually becoming shallow C-shaped or V-shaped in different
parts; protoxylem in base of leaf traces single, endarch; when leaf traces pass through
inner cortex, protoxylem biturcating. Petiole bases without stipular expansion, probablyloosely embracing the stem; xylem strand of potiole trace shallow C-shaped, surrounded by selerenchyma; sclerotic ring round, connected with single sclerenchyma mass in the concavity of the petiole trace. Root arising singly from leaf trace, diarch, with inner and outer cortex.
P. plenasioides is represented by a rhizome; stem more than 4 cm in diameter;
stele actophloic dictyoxylic siphonostele; xylem cylider with about 20 tracheids in
radial thickness, dissected by leaf gaps; xylem bundle U-, O-, or crosier- (i.e. query-)
shaped; pith and inner cortex parenchymatous, with many groups of secretory cells;
leaf trace C-shaped, its base containing two endarch protoxylem groups; root diareh,with inner and outer cortex, arising singly from leaf trace or its base. 相似文献