徐氏蕨属——中国云南早泥盆世陆地植物的一个新属

中国科学院大学学报

徐氏蕨属——中国云南早泥盆世陆地植物的一个新属

李承森

(中国科学院植物研究所)

收稿日期:1900-01-01 修回日期:1900-01-01 出版日期:1982-08-18 发布日期:1982-08-18
通讯作者: 李承森

Hsüa robusta, a new land plant from the Lower Devonian of Yunnan, China

Li Cheng-Sen

(Institute of Botany, Academia Sinica)

Received:1900-01-01 Revised:1900-01-01 Online:1982-08-18 Published:1982-08-18
Contact: Li Cheng-Sen

摘要/Abstract

Abstract:

A new psilophytic plant, Hsüa robusta, is found in the Xujiachong Formation

(Emsian) of the Lower Devonian from the Qüjing (= Kütsing) district of Yunnan,

China. This plant is tentatively referred to the Cooksoniaceae of Rhyniales.

Hsüa gen. nov.

Type species: Hsüa robusta (Li et Cai) C. S. Li.

Diagnosis: Plants erect and then creeping. Main axes dividing pseudomonopodial-

ly and bearing dichotomous lateral branches which somewhat differentiate into vegeta,

tire and fertile ones, with dichotomous root-like and rhizophore-like appendages. Spo-

rangia terminal, round to reniform or wide reniform, dehiscing along distal margin into

two equal halves. Spores homosporous, trilete. Stomata anomocytic. Protostele cen-

trarch.

Hsüia robusta (Li et Cai) C. S. Li, comb. nov.

Cooksonia zhanyiensis Li et Cai, Acta Geologica Sinica, 52 (1) 1978, p. 10, pl. II,

fig. 6.——Taeniocrada robusta Li et Cai,ib. p. 10, pl. II, fig. 7—14.

Diagnosis: Characters same as in generic diagnosis. Main axes 6—10 mm wide and

at least 24 cm long, with vascular strands 1.2—2.4 mm acr oss. Fertile branches 3—4

times equally or unequally dichotomous, 10—1.5 mm in width and up to 11 cm in length,

possessing a vascular bundle of 0.5 mm in its greatest diameter. Branches circinately

coiled in apical regions. Axial tubercles, root-like and rhizophore— like appendages aris-

ing from the main axes usually anterior to the lateral branches. Axial tubercle round

with a diameter of 2.2—2.4 mm, having a vascular bundle about l mm across. Root-

like branches 3 times bifurcate, 1—0.3 mm wide and up to 1.5 cm long, with a vascular

bundle about 0.1 mm across. Rhizophore-like appendages forked, 3—1.7 mm in width,

possessing a vascular bundle of 0.7 mm in its greatest diameter. Root-like protuberances

sometimes arising from rhilzophore-like branches. Epidermal cells of axes generally

elongate, measuring 60—290μby 25—60 μ. Stomata mainly fusiform, 90—110 μ long

and 50—60μ wide, consisting of a pair of guard cells enclosing a pore 6—15μ in length

and 1—3μ in width. Cuticle of guard cells quite thick. Stomatal density about 5 per

mm². Sporangia 0.8—4.2 mm high, 1.0—8.2 mm across, usually having a dehiscent distal

border which measures 50—100μ broad. Demarcation between sporangium and its stalk

quite clear. Epidermal cells of basal part of sporangial walls elongate, about 100 μ long

and 30μ wide, but those of distal part isodiametrally polygonal, about 50μ in diame-

ter. Stomata, radially arranged scattering over sporangial walls, generally round about

50μ in diameter and 50 per sporangium. Spores round, 18—36μ (average 27μ) indiameter, and smooth. Tracheids of protoxylem about 10μ across; those of metaxylem

about 30μ across, with scalariform thickening.

This plant is similar to Renalia hueberi Gensel in general morphology, but differs

from the latter in possessing root-like and rhizophore-like branches.

The generic name is derived from Prof. Hsü Jen.

This paper is a thesis for M. Sc.

李承森. 徐氏蕨属——中国云南早泥盆世陆地植物的一个新属[J]. 中国科学院大学学报.

Li Cheng-Sen. Hsüa robusta, a new land plant from the Lower Devonian of Yunnan, China[J]. .