Renalia


Renalia is a genus of extinct vascular plants from the Early Devonian. It was first described in 1976 from compressed fossils in the Battery Point Formation. It is difficult to reconstruct the original form of the complete plant, but it appears to have consisted of leafless branching stems whose side branches had sporangia at their tips. It is regarded as an early relative of the lycophytes.

Description

The species R. hueberi was described by Patricia G. Gensel in 1976 from compressed fossils. As with all compressions, it is difficult to reconstruct the entire plant, but the sporophyte is thought to have been about 30 cm tall, with bare stems up to 1.5 mm wide. The main stem had lateral branches which divided into two equal branches several times. Tracheids were present in the stems. The rounded to reniform sporangia were born at the tips of the lateral branches and dehisced along the distal margin into two equal parts. The spores were trilete.
Two further species, R. grabertii and R. major were described later by Schweitzer. The sporangia are similarly reniform, differing in their placement. In R. major, they are inserted laterally on the stem on small stalks, too short to be called branches.

Phylogeny

The absence of leaves, the presence of vascular tissue, the terminal position of the sporangia and the form of the branching of the stems suggest a relationship with the Rhyniaceae; however, the shape of the sporangia and the form of their dehiscence suggest a relationship with the lycophytes. Hence the position of the genus in the cladogram for the polysporangiophytes which Crane et al. published in 2004; Renalia is placed basal to the lycophytes.