STUDIES OF FRESHWATER RED ALGAE

Abstract

BATRACHOSPERMUM LOUISIANAE Skuj a. (fig. 18).-Plants of the following collections were identified as this species: (1) on submerged leaves and stems in slow stream near Lacombe, St. Tammany Parish, La., June 6, 1947; (2) as preceding, July 19, 1947; (3) as preceding, October 15, 1947; (4) stream south of Abita Springs, St. Tammany Parish, La., December 3, 1948; (5) stream near Mandeville, St. Tammany Parish, La., December 3, 1948; (6) stream near Angie, Washington Parish, La., December 4, 1948. The first three collections were in the chantransia stage but the Abita Springs and Angie collections included sexual plants, chantransial plants and critical material establishing the relationship. Historically this plant is the most interesting of the many species of freshwater red algae in Louisiana. It was collected near Mandeville, St. Tammany Parish, La., on April 20, 1891, by A. B. Langlois, who labelled it B. moniliforme. In 1931 Skuja created a Section Conto-rta to accord a place for plants differentiated from other species of Batrachospermum by the possession of twisted branches, since which time more than twenty spe1 Received for publication February 28, 1949. cies have been assigned to the Section. B. louisianae Skuja is one of the few species thus far reported from the United States which fall within Section Contorta. The sexual plants collected comprised bright blue-green tufts of finely-textured fronds, centrally dark to black, which upon drying resolved mostly into fan-shaped segments. In the larger plants these subordinate portions evidenced sub-dichotomous basal branching. The height did not exceed 5 cm. The plants had but little resemblance to other species collected within the state and in fact differed appreciably in superficial features from the plants collected at Mandeville by Langlois. Microscopically, however, the critical features were in excellent agreement, and the differences were attributed to age and environmental factors. The species has been reported also from Mosquito Inlet, Florida, where it was collected by R. Thaxter in January, 1898. The plants collected were monoecious and bore a strong resemblance to Sirodotia, a fact attributable to the placement of the carpogones, which were sessile at the base of whorl elements. On this account the cystocarps were flattened basally, and because the axes were twisted, the resultant outline or silhouette of the plants was such a.s to suggest asymmetric development. In some instances the cystocarps which had developed at adjoining nodes had become confluent. The trichogynes were small simple club-shaped structures. The spermatangia were also small, and were borne terminally on unmodified whorl elements; also in small numbers on internodal bracts. On old denuded stems there sometimes developed a profusion of vegetative monospores. The chantransia plants consisted of blue-green tufts up to 2 cm. in height. These plants coated submerged structures in such a way as to suggest a heavy growth of Tolypothrix. The young sexual plants often originated at some distance from the bases of the chantransial filaments and developed as blue-green ball-like growths, from the lower cells of which budded entwining rhizoidal strands. The chantransia plants were almost devoid of gelatinous material and did not adhere to filter paper upon drying, in this respect differing from the chantransia plants of the great majority of species of Batrachospermum. Neither in these, nor in the sexual plants, was there noted any outward evidence of the presence of a red pigment. BATRACHOSPERMUM VAGUM (Roth) Ag. (fig. 915).-Plants of the following collections were identified as this species: (1) stream west of Leesville, Vernon Parish, La., April 27, 1945; (2) stream near Folsom, St. Tammany Parish, La., October