Synthetic and wild Asplenium gravesii

Abstract

Asplenium gravesii Maxon, a rare spleenwort known only from a few localities, has been considered a hybrid of A. bradleyi and A. pinnatifidum. A. gravesii was collected again at the type locality in 1954, and was also synthesized by sowing spores of the parents together in culture. Leaf pattern of both synthetic and wild forms is more regular and symmetric than that of one of the parents, A. pinnatifidum. The synthetic differs from the wild form in having (a) pinnae more remote; (b) pinnae narrower at the base; (c) laminar margins less deeply dentate; and (d) sori medial rather than infra-medial. Chromosome pairing behavior of A. gravesii conforms approximately to that which would be predicted if the parents, A. bradleyi and A. pinnatifidum, are allopolyploid hybrids, A. montanum X platyneuron and A. montanum X rhizophyllum respectively. To reduce the confusion in identification that exists because of resemblances of A. gravesii to several of its relatives, a key is here provided. © 1957, The New York Botanical Garden. All rights reserved.