An "Intergeneric" Hybrid: Aglaomorpha X Drynaria

Abstract

In 1969 I was asked to identify a garden plant obviously related to Aglaomorpha, but not matching any known species. I was uncertain whether the plant was a variation of Aglaomorpha coronans (Wall. ex Mett.) Copel. or a hybrid involving that species. In 1972, herbarium specimens were sent to C. V. Morton of the United States National Herbarium and to F. M. Jarrett of the Royal Botanic Gardens, Kew. Mr. Morton wrote that the plant was near A. coronans but hardly that species. Dr. Jarrett wondered if it might possibly be a hybrid between Aglaomorpha and Drynaria. Others thought it might be a variant of A. coronans. From the study of Drynarioideae by Roos (1985), I was able to ascertain that the plant was not a variant of A. coronans, nor the hybrid (A. xleporella), nor any other taxa treated in his monograph. The original source of this unidentified plant was Mr. Al Roberts, a nurseryman who specialized in ferns and was the proprietor of the former Robert's Subtropical Gardens, Los Angeles, California. Before the appearance of this unidentified plant, Mr. Roberts had related to me that he routinely planted different spores together for convenience and had done so with species received from the Berkeley Botanical Gardens, University of California, Berkeley, California. This led me to suspect the unknown plant was a hybrid. Unmistakably present in this putative hybrid are characteristics of A. coronans, a plant that was well known in cultivation long before 1954 and was often grown by fern collectors. Herbarium records indicate that Drynaria rigidula (Sw.) Bedd. was growing at the Berkeley Botanical Garden in 1953 and had been distributed to tradesmen; herbarium records indicate Mr. Roberts had this species by 1958. He apparently sowed A. coronans together with D. rigidula and produced this hybrid sometime between 1953 and before 1959, the year his nursery closed. During this period my records indicate that other aglaomorphas and drynarias were in local cultivation, and I therefore examined them as possible parents. These species were found to be unlikely parents as the putative hybrid has no hint of the strongly contracted fertile lobes and relatively large, consistently round sori of A. meyeniana Schott, nor the immense fronds and many small scattered sori of A. heraclea (Kunze) Copel., nor the round sori in two rows of D. quercifolia (L.) J. Sm. If A. coronans is one parent, the hybrid's pinnatisect blades and notched pinnae rule out these unlikely parents further, as they all have pinnatifid blades and entire pinnae. This left D. rigidula with its pinnate fronds and serrate margins as the most plausible second parent. Also, all of the unlikely parents are tender plants, while the proposed parents and their putative hybrid are hardier.