J Integr Plant Biol. ›› 1973, Vol. 15 ›› Issue (2): -.

• Research Articles •    

The Morphology of Archangiopteris Christ et Gies. and Its Reletionship with Angiopteris Hoffm.

Chang Chih-yü   

Abstract: The present paper is devoted to a study of the basic morphological and anatomicalcharacteristics of the endemic Sino-Vietnamese genus Archangiopteris Christ et Gies. The result of the study has shown that Archangiopteris differs from Angiopteris iioffm in a number of important features. Morphologically, it is distinguished from Angiopteris by rather long-creeping, dorsiventral rhizome with distichous leaves(fronds), which are, as a rule, simply impari-pinnate, with usually 1–5 pairs of lateral pinnae; the fleshy stipe being provided with 1 or rarely 4–5 geniculate swellingsat the middle and clad in the lower part in coarsely dentate thin scales; the linear soriconsisting of 60–260 (sometimes 20 in the bipinnate-leaved species) sporangia,situated midway between the costa and leaf margin and mingled from underneathwith branched hair-like malticelinlar paraphyses; and by a spore-output per sporan-glum of 1800–1900 spores which are sphaerotetraedric, translucent, with finelyechinose exospores. Anatomically, Archangiopteris, unlike Angiopteris, has a dictyos-tele consisting of one single vascular cylinder, also dorsiventral in structure., withsingle leaf-trace from its dorsal side and root trace from its ventral side, and the protoxylem elements are endarch both in the rhizome and the petiole. The results of comparison indicated, however, that Archangiopteris is closelyrelated to Angiopteris. It is quite possible that the genus is derived from Angiopterisby way of such simply pinnate-leaved species of Angiopteris as A. pinnata Ching, to Archangiopteris cadicri Tard-Blot et C. Chr. The morphological and anatomical features as indicated above tend to show that the genus is more advanced than Angiopteris. The characteristic fleshy no dose swelling of the stipe in Archangiopteris has been also anatomically studied. It has been considered as a structure of an adaptive nature in response to its feebly lighted habitat, whereby controlling the orientation of fronds in relation to the direction and intensity of the sun's rays and thus enabling the plant to absorb enough light energy for photosynthesis. The problem of the similarity in the external morphology and internal structure of Archangiopteris to the sporeling of Angiopteris has been also studied both in the field and in the laboratory. This phenomenon has been explained as an example of what is known as juvenile maturity in the plant life (neoteny). Archangiopteris, when first established as a new genus by Christ and Giesenhagenin 1899, was considered as a primitive fern genus of Marattiales, a view, which the present study of the genus does not prove to be correct, for, although Archangiopteris,in contrast with Angiopteris, has a much more simple external morphology and internalstructure, this simplification mw not necessarily reflect the primitiveness of the genus, but perhaps rather as a result of juvenile maturity. It may be assumed thatin the course of evolution through great geological ages, the genus in adapting itselfto the particular environment has developed a series of advanced characters as mentioned at the outset. In his study of taxonomy of the genus Archangiopteris, R. C. Ching (1958) pointed out that the genus was a direct derivative from Angiopteris, aview which agrees well with the result of the observations by the present writer.

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