On Systematic Position of Pterygocalyx (Gentianaceae)-文献传递-植物通论文库

作者：CHEN Shi-Long, HO Ting-Nong, HONG De-Yuan

期刊：植物分类学报 1998年 1期

Abstract:

The gross morphology, floral anatomy, embryology, pollen and karyotypes of

Pterygocalyx volubilis were studied. The results are used to reevaluate the taxonomic status

of the monotypic genus Pterygocalyx. Pterygocalyx volubilis has epipetalous glands. There

are 16 bundles in calyx tube and 12 bundles in corolla tube, the calyx and corolla bundles are

different in origin. Each carpel has one dorsal and two ventral bundles. Flowers are protan-

drous. The anther is 4-sporangiate. The development of anther walls conforms to the di-

cotylendonous type . The tapetum is of glandular type, dual origin, and binucleate cells at the

late stage. The epidermis and part of endothecium persist; epidermisis fibrous-thickened.

Cytokinesis in the microsporocyte meiosis is simultaneous, and tetrads are tetrahedral. Pollen

grains shed at the 3-celled condition. The ovary is bicarpellate and unilocular. The placenta-

tion is of superficial placentae with 25～40 series of ovules. The ovule is unitegmic, tenuinu-

cellar and anatropous. The embryo sac originates from a single archesporial cell. The chalazal

megaspore in linear tetrad becomes the functional one. The development of embryo sac is of

the Polygonum type. Before fertilization, two polar nuclei fuse into a secondary nucleus.

Three antipodals persist, become much enlarged, and function as haustorium. The develop-

ment of the endosperm is of the Nuclear type. Pollen grains of Pterygocalyx are spheroidal,

32.8×34.2 μm in size with exine ornamentation being reticulate. The chromosome number

of Pterygocalyx is 2n＝26, with the basic number x＝13. The karyotype is formulated as 2n

=26＝8m+4sm+2st+2t, belonging to “2A” type in Stebbins‘classification. The genus

Pterygocalyx is closely related to Gentianopsis . It is better to treat Pterygocalyx as an in-

dependent genus.

On Systematic Position of Pterygocalyx (Gentianaceae)