Growing on old wood, bark, etc.; rare. Sporangium .4-.5 mm. in diameter, the stipe two or three times as long, the lime-nodules about the size of the spores. The species much resembles some of the forms of P. obrusseum, but is to be distinguished by its central mass of lime and the small spores.
5. Physarum compactum Wingate. Sporangium depressed-globose, the base slightly umbilicate, stipitate, cernuous; the wall a thin, violaceous membrane, rugulose and iridescent, studded with large and thick, snow-white, roundish or elliptic scales of lime, at maturity splitting from the apex downward into several segments. Stipe long, rather weak, bent and flexuous, tapering upward, longitudinally rugulose, from snow-white to whitish-ochre and smoky-white, usually brownish at the base, and arising from a thin hypothallus. Capillitium a delicate net-work of very slender threads, with no expansions at the angles; the lime mostly concentrated in one large, snow-white nodule at the center, a few very small, roundish nodules scattered through the net-work. Spores globose, very minutely warted, violaceous, 7–9 mic. in diameter.
Growing on old wood, mosses, etc.; a common species. Sporangium .4-.5 mm. in diameter, the stipe two or three times this length. Tilmadoche compacta Wingate. It is doubtful if Tilmadoche columbina Rost. belongs to this species. According to Lister, Lepidoderma stellatum Massee, is the same as this species, and if it be objected to the name that there is already a Physarum compactum Ehrenberg, it may have to be called Physarum stellatum.
b. Sporangium more or less irregular.
6. Physarum leucophæum Fr. Sporangium globose or depressed-globose, more or less irregular, the base never umbilicate, stipitate or subsessile; the wall a thin violaceous membrane, rugulose and iridescent, with a thin coat of small white scales and granules of lime, or sometimes nearly naked. Stipe variable in length, sometimes very short or quite obsolete, occasionally a few of them confluent, wrinkled, and sulcate, brown below, paler or whitish above. Capillitium a dense irregular net-work of slender tubules, more or less expanded at the angles; the nodules of lime white, small, roundish, or angular, few and scattered. Spores globose, very minutely warted, violaceous, 8–10 mic. in diameter.
Growing on old wood, bark, leaves, etc. The sporangium .5-.7 mm. in diameter, the stipe about the same length, or shorter, and sometimes wanting. The lime on the wall and in the capillitium is never abundant and sometimes extremely scanty. Rostafinski's presentation of this species applies well to our specimens.
7. Physarum connexum Link. Sporangia subglobose, depressed, more or less irregular, sometimes confluent, stipitate, or subsessile; the wall a thin violaceous, or brownish membrane, rugulose, thickly covered with small white roundish scales of lime, which sometimes accumulate so as to make the surface rough and uneven. Stipe short, thick, rugulose, from snow white to smoky or sooty, especially toward the base, sometimes with a scanty calcareous hypothallus. Capillitium a loose net-work of tubules, much expanded at the angles; the nodules of lime small, white, rather numerous, ellipsoidal or fusiform, sometimes confluent and elongated. Spores irregularly globose, minutely warted, dark violaceous, 9–11 mic. in diameter.
Growing on old wood and bark. Sporangium .6–1.0 mm. in diameter, the stipe usually shorter than the diameter, sometimes very short; the lime-nodules about the thickness of the spores. This is a larger and rougher species than P. leucophæum, the sporangium is more often irregular and the spores darker colored. P. confluens and P. connexum of Link. [See Plate XIV. Fig. 59.]
8. Physarum compressum A. & S. Sporangium laterally compressed and much flattened, subreniform, stipitate or subsessile; the wall a thin violaceous or brownish membrane, rugulose, thickly covered with small white roundish nodules of lime, similar to those in the capillitium. Stipe short, brown or blackish at least below, sometimes pallid or grayish above, longitudinally rugulose. Capillitium of slender tubules, forming a loose net-work; the nodules of lime small, white, very numerous, roundish or ellipsoidal, often confluent end to end. Spores irregularly globose or angular, minutely warted, dark violaceous, 11–14 mic. in diameter.
Growing on old stalks and leaves of Zea mays. Sporangium variable, .6–1.0 mm. in breadth, the stipe 1 mm. or less in length; the lime nodules about the thickness of the spores. According to Saccardo this species is the same as Physarum nephroedium Rost.