裸子植物的幼苗类型及其进化关系

中国科学院大学学报

裸子植物的幼苗类型及其进化关系

叶能干, 芶光前, 廖海民, 张著林

收稿日期:1900-01-01 修回日期:1900-01-01 出版日期:1993-11-18 发布日期:1993-11-18
通讯作者: 叶能干

The Seedling Types of Gymnosperms and Their Evolutionary Relationships

Ye Neng-gan, Gou Guang-qian, Liao Hai-min, Zhang Zhu-lin

Received:1900-01-01 Revised:1900-01-01 Online:1993-11-18 Published:1993-11-18
Contact: Ye Neng-gan

摘要/Abstract

摘要：

裸子植物的幼苗可分为3个类型、8个亚型。即：1．苏铁型，包括苏铁亚型、银杏亚型、南洋杉亚型；2．松型，包括杉亚型，松亚型，麻黄亚型；3．买麻膝型，包括买麻滕亚型，百岁兰亚型。类型和亚型都有特征描述，并有一个检索表。文中首先讨论了种子的起源是多元的，因而裸子植物的起源也应是多元的，是前裸子植物不同类型平行进化的结果。又根据裸子植物幼苗类型的形态特征，提出裸子植物有4条进化路线，即：苏铁路线，银杏路线，松柏路线和买麻滕路线。还讨论幼苗类型之间的进化关系，认为除买麻滕型幼苗因其形态特殊有自己独特的发展路线外，总的趋势是由留土萌发向出土萌发发展。

关键词: 裸子植物, 幼苗类型, 演化路线, 进化关系

Abstract:

The three types and eight subtypes of seedlings are recognized in the

gymnosperms in the present paper. They are: 1. The Cycas Type: cotyledons 2,

with absorptive function, absorbing nutrients from the endosperm (gametophyte);

hypogeal; including three subtypes: (1) The Cycas Subtype: internodes not elon-

gated; leaves simple, pinnate; (2) The Ginkgo Subtype: internodes elongated;

leaves fan-shaped; (3) The Araucaria Subtype: internodes elongated; leaves linear.

2. The Pinus Type: cotyledons 2 to numberous, with both absorptive and

photosynthetic Functions; epigeal; including three subtypes: (1) The Cunninghamia

Subtype: cotyledons 2- 4; internodes elongated; leaves linear; (2) The Pinus

Subtype: cotyledons numerous; internodes not elongated; leaves needle-like (3)

The Ephedra Subtype: cotyledons 2; internodes elongated; leaves scaly. 3. The

Gnetum Type: with an absorptive function foot at the base of the hypocotyl, ab-

sorbing nutrients from the endosperm; cotyledons 2, with photosynthetic function,

epigeal, containing two subtypes: (1) The Gnetum Subtype: cotyledons similar to

foliar leaves, like the pinninerved leaves of the Dicotyledons; internodes elongated;

(2) The Welwitschia Subtype: cotyledons linear, internodes absent, the whole

plant with only a pair of leaves. Detailed descriptions and a key to the three

types and eight subtypes are presented in the paper. It is considered that the ori-

gin of the gymnosperms is not monophyletic but polyphyletic. That is to say, the

seed of gymnosperm is polyphyletic as a result of parallel evolution in different

groups of the progymnosperms. According to the morphological characters of the

seedling types we propose that there have existed four evolutionary lines in the

gymnosperms, namely: the Cycas line, the Ginkgo line, the Conifer line and the

Gnetum line, and the evolutionary process of each line is explained. The evolu-

tionary relationships among the three types and eight subtypes are discussed.

There is a foot in the Gnetum Type, which is uncomparable with any seedling

type of seed plants, since it has its unique developed line and differentiated into

the Gnetum Subtype and the Welwitschia Subtype. The evolutionary tendency is

from hypogeal to epigeal in the other types and subtypes. Cycas and Ginkgo are

relict with seedling types belonging to the Cycas Subtype and the Ginkgo Subtype

respectively, which have maintained an ancient character-hypogeal. Therefore,

the evolution of seedling types is from the Araucaria Subtype to the Pinus Type,

and the latter itself differentiated into three subtypes. Moreover, it is explained

why there are stomata on the hypogeal cotyledons of Cycas and Ginkgo when the

footed embryo of the progymnosperms changed to the embryo of the Cycas type

via neoteny, the foot was lost, and the first two leaves on the stem tip were ar-

rested, changing to the cotyledons of the Cycas Type and replacing the foot of the

progymnosperms as an absorptive organ. The stomata on the cotyledon epidermis

of Cycas and Ginkgo are a residue of the first two leaves of the progymnosperms.

Key words: Gymnosperms, Seedling type, Evolutionary line, evolutionary relationship

叶能干, 芶光前, 廖海民, 张著林. 裸子植物的幼苗类型及其进化关系[J]. 中国科学院大学学报.

Ye Neng-gan, Gou Guang-qian, Liao Hai-min, Zhang Zhu-lin. The Seedling Types of Gymnosperms and Their Evolutionary Relationships[J]. .

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