Monographs Details: Stigonema congestum N.L.Gardner
Authority: Gardner, Nathaniel L. 1927. New Myxophyceae from Porto Rico. Mem. New York Bot. Gard. 7: 1-144. pl. 1-23.
Description:Species Description - Filaments 150—225 µ long, 12-15 µ diam., very much contorted and intertwined, forming a thin, dense stratum; branches numerous, of 2 or 3 orders, all of similar diameters, slightly constricted at the base, arising at right angles, but soon bending upward; cells uniseriate or when aged in part pluriseriate, closely crowded, irregular in form, about one-half the diameter long, homogeneous; cross-walls thin; tegument thin, firm, smooth, homogeneous, dark brown; heterocysts fairly abundant.

Distribution and Ecology - Growing on stones near Hacienda Catalina, Palmer, no. 791, type; on rocks near San Lorenzo, no. 503; in a stream about five kilometers east of Coamo, no. 1886 e; on " Fly tteblok," west of Humacao, nos. 570 a and 571 b; on red earth by the road, Hacienda Catalina, Palmer, no. 776; on red earth by the road north of Maricao, no. 1241; on trunk of a palm tree at Santurce, no. 23; on lava north of Sabana Grande, no. 923 a and 936.

Discussion:PLATE 21, FIGURE 52