THE STRUCTURE AND REPRODUCTION OF GLAPHYRYMENIA PUSTULOSA

NORRIS, R. E. (U. Minnesota, Minneapolis.) The structure and reproduction of Glaphyrymenia pustulosa. Amer. Jour. Bot. 48(3): 262-268. Illus. 1961.-Specimens of Glaphyrymenia pustulosa, a red alga from Australia that has seldom been found, were collected recently. The specimens were examined particularly with respect to development of the vegetative tissues and the formation of the female reproductive apparatus and gonimoblast. The vegetative structure is primitive in the Kallymeniaceae and structural characteristics are present that are similar to the Cryptonemiaceae and Dumontiaceae. The female reproductive system has a monocarpogonial carpogonial branch apparatus and an auxiliary cell that is borne on a separate system that does not have a carpogonial branch. After fertilization, stages in the development of the gonimoblast are similar to those of Kallymenia and Pugetia. THE HISTORY of Glaphyrymenia pustulosa J. Agardh (1885, p. 52), the type species of the genus, was reviewed by Norris, 1957, p. 301. At that time it was shown that Glaphyrymenia is possibly a member of the Kallymeniaceae, a conclusion that was verified by a later report (Norris, 1959, p. 284). Further details reported here on the anatomy and reproduction of Glaphyrymenia pustulosa have been accumulated more recently. MATERIALS AND METHODS.-Glaphyrymenia pustulosa has rarely been found, but it was my good fortune to collect fertile specimens in the drift at Elliston, on the Eyre Peninsula of South Australia on February 27, 1959 (collection number 1664).2 Several plants were dried for herbarium voucher specimens, and parts of thalli that were to be used for investigations on internal anatomy and studies on reproduction were fixed in a weak Karpetchenko solution or in a solution of 4% formaldehyde. The extremely lubricous nature of the thallus made it difficult to prepare good squashed preparations for study of the female reproductive system. Most of the details of these structures as well as the information on the internal anatomy of the thallus were gained by observations on sections sliced with a freezing microtome. Staining was done with Mayer's Acid Haemalum according to the procedure used by Norris (1957, p. 253). The sections were mounted in glycerine jelly rather than in Euparal, since the alcohol medium necessary for the latter technique caused excessive shrinkage and torsion of the sections. STRUCTURE OF THE THALLUS.-The blade of Glaphyrymenia pustulosa is flat, approximately 1500 A thick in mature regionis, expanded and very gelatinous. The thallus may be rounded or deeply 1 Received for publication September 16, 1960. The author is grateful to the United States National Science Foundation for its support of this investigation (Grant no. G-6697). 2 I would like to thank Dr. H. B. S. Womersley for organizing the field trip on which these specimens were collected. lobed (fig. 1), and often the margin is irregularly otched. Usually the thallus is broader than long, the average dimensions of 6 thalli being 14.6 cm. long, 19.1 cm. wide. The holdfast is flat and irregularly expanded on one side; the margin is thin and finely dentate. There is no definite stipe. Sections of the holdfast (fig. 2) demonstrated that a cortical region is present only on the dorsal side of the holdfast. On both the ventral and the dorsal sides near the margin of the holdfast, rhizoidal filaments similar to medullary filaments are present. Where the holdfast is in contact with the substratum, the rhizoidal filaments are very contorted and grow in intimate contact with it. In other regions of the holdfast, the rhizoidal filaments grow parallel to one another, with apical cells directed downward. There are 2 bits of evidence thiat the holdfast is perennial but that the blade may be annual. First, some of the female thalli have mature cystocarps close to the margin of the thallus, an indication that growth had stopped and that the erect thallus is produced seasonally. Second, the sections showed a zone where growth had stopped at the end of the previous growing season in the region of the holdfast adjacent to the base of the blade (fig. 2). It was possible to see the stub of an old blade where it had broken from the holdfast. A bulge on the upper part of the holdfast probably represents the initial stage in the development of a new blade. A second region of active growth was adjacent to the origin of the present blade. It could not be determined with certainty whether this area was developing into a new blade or expanding the area of the holdfast. In section, the blade of Glapithyrymenia pitstulosa has a medulla of loosely interwoven filaments and a cortex of small cells that are tightly packed (fig. 3, 4). Mature filaments in the medulla are composed of slender cells with angular ends and with few or no chromatophores. Young filaments are of much shorter and thicker cells with rounided ends