This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
1814. Cathartolinum rigidum Small, N. A. Fl. 251:
Perennial (?), 6'-15' high, branched, glaucous, glabrous or puberulent. Branches stiff, more or less angular; leaves erect, linear or linear-lanceolate, 4"-12" long, 1/2"-1" wide, acute or mu-cronate, the upper ones glandular-serrulate or ciliate; stipular glands minute, globose, sometimes wanting; flowers yellow, 9"-15" broad; sepals lanceolate, acute or awn-pointed, glandular-serrulate, the outer ones becoming 3"-4" long; petals cuneate-obovate, twice the length of the sepals; styles separate only at the summit; capsule ovoid, 5-valved, shorter than the sepals, 2"-2i" long.
Linum Berlandieri Hook. Bot. Mag. sub pl. 3480. 1836.
C. Berlandieri Small, N. A. Fl. 251: 82. 1907.
Annual (?),2 1/2'-16' high, often much-branched, bright green and sometimes glaucescent when young. Branches ascending, striate-winged; leaves spreading or ascending, linear to narrowly linear-lanceolate, mostly 7"-2o" long, acuminate; stipular glands, when present, short; bracts glandular-toothed; flowers bright yellow, 16"-24" broad; sepals lanceolate, the outer ones becoming 4 1/2"-5 1/2" long, all evenly glandular-toothed; petals obovate, 8 1/2"-11" long; capsule ovoid, 2"-2i" long.
In dry soil, Kansas and Colorado to Texas. Spring.
Cathartolinum compáctum (A. Nelson) Small, a species related to C. rigidum, ranges from the Rocky Mountain region into North Dakota and Kansas. It is a low dull green plant with small flowers, the petals less than 5" long.
Millegrana Radiola (L.) Druce (Radiola Linoides Roth), the All-seed of Europe, has been found on Cape Breton. The genus differs from Linum and Cathartolinum in its 4-parted flowers.