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Collema curtisporum Degel.

Short-spored Jelly Lichen

Collemataceae

General Description: A small, black foliose lichen that has a gelatinous texture when wet. The thallus is generally around 2 cm, but up to 4 cm broad and has broadly rounded lobes. Apothecia are usually present, but isidia and soredia are lacking. Spores are 4-septate, hyaline, 20-40 x 3-4.5 um, straight or curved, and with blunt ends.

Field Identification Tips: Positive field identification is difficult. Examination of spore length under a compound light microscope is the only reliable means to distinguish C. curtisporum from C. nigrescens.

Similar Species: Collema furfuraceum is a common associate, but can be distinguished by the distinctive ridged and blistered appearance of the thallus, along with abundant isidia, and the usual lack of apothecia. The thallus of C. nigrescens is very similar to C. curtisporum, and spore examination is necessary to reliably distinguish these two species. However their known ranges do not overlap, as C. nigrescens occurs west of the Cascades. Care must also be taken not to confuse species of Leptogium with Collema.

Habitat: Moist riparian forests, where almost always on the bark of Populus trichocarpa (black cottonwood).

Global Distribution: Between the Cascade and Rocky Mountain crests in eastern Washington, northern Idaho, northeastern Oregon, and western Montana.

Idaho Distribution: Known from the Lochsa, North Fork Clearwater, St. Maries, St. Joe, Couer d' Alene, and Clark Fork river bottoms, and from around Priest Lake.

References:

McCune, B., and T. Goward. 1995. Macrolichens of the Northern Rocky Mountains. Mad River Press, Inc. Eureka, California. 208 pp.

McCune, B., and L. Geiser. 1997. Macrolichens of the Pacific Northwest: the first comprehensive guide to northwest macrolichens. Oregon State University Press, Corvallis. 386 pp.