STUDIES ON CONIOPTERIS TATUNGENSIS OF JURASSIC FROM WESTERN HILLS OF BEIJING

Coniopteris tatungensis is a common element in the Jurassic floras. This paper deals with new collection of C. tatungensis from Beijing and reports the details of the reproductive feature of this plant observed by SEM. The taxonomical assignment and geographical distribution of C. tatungensis are discussed also in this paper.In C. tatungensis Sze., fronds at least 2～3 times pinnate, with main rachis slender. Pinnae alternate, linear to linear lanceolate . The first pair of pinnules nearly opposite, others becoming alternate. First pinnule on the acroscopic side of the penultimate pinnae well developed and divided into 2～3 lobes, while the first pinnule on the basiscopic side obviously weak, much smaller and narrower, usually divided into 1～2 lobes. Reproductive fronds fully or partly fertile, the latter with first pinnules on the acroscopic side bearing fewer sori. The lamina of pinnule strongly reduced bearing an elliptical sorus distally. Number of sori mostly 1 per pinnule, but often 2～3 at the basal part of penultimate pinnae. Indusia cup shaped. Sori containing at least 12 sporangia. Sporangia shortly stalked, not all at the same age in a sorus. Sporangia rounded to ellipsoidal. Annuli not complete, nearly vertical, consisting of about 15～20 thicked cells. Spores rounded triangular, trilete, laesurae reaching almost to equator.