AN EXAMPLE OF SPORANGIAL INDEHISCENCE IN THE FILICOPSIDA.

Abstract

Asplenium haussknecktii Godet & Reuter is a small fern which grows in limestone mountains at high altitudes and has a distribution extending from Crete and Turkey in the west to Iraq, Iran and the Caucasus in the east. It is known to be an allotetraploid species which has originated from chromosomal doubling in a hybrid between the diploid species A. aegaeum Lovis et al. and A. ruta-muraria L. subsp. dolomiticum Lovis & Reichstein (Brownsey, 1976a). A. lepidum Presl, a plant found in the limestone mountains of central and southern Europe, is also known to be allotetraploid (Lovis, Melzer and Reichstein, 1966; Vida, 1970), and, indeed, it is now thought that the two taxa share the same parentage and are really only subspecies of one polymorphic aggregate extending across Europe and part of Asia, (Brownsey, 1976b). Both taxa consist of small, isolated, relatively uniform populations throughout their areas of distribution. Nevertheless, investigation of plants raised in cultivation from spores collected in the wild has shown that there is considerable morphological variation between populations and that each one can be readily distinguished by its characteristic and consistent combination of frond morphology and growth form. The two species differ in the degree of dissection of the frond but their ranges of variation with respect to this character overlap, and the only truly diagnostic taxonomic character noted by earlier authors (Milde, 1867; Reichstein et al., 1973) is the presence of glandular hairs on the lamina and rachis of A. lepidumn. The present investigation has confirmed the value of this character and has furthermore demonstrated that this distinction be-