4. Sclerolinon C. M. Rogers, Madroño. 18: 182, figs. 2–6. 1966.
Hard flax [Greek skleros, hard, and linon, flax, alluding to fruit] Hard flax [Greek skleros, hard, and linon, flax, alluding to fruit]
Herbs, annual, glabrous, sometimes glaucous. Stems erect, usually unbranched, sometimes branched proximally and corymbosely branched distally. Leaves persistent, opposite, or distal sometimes alternate; stipular glands absent; blade oblong to elliptic, margins entire, or distal leaves sometimes serrate. Inflorescences cymes. Pedicels articulated. Flowers: sepals persistent, 5, connate at base, unequal in size, margins glandular-toothed, glabrous; petals 5, distinct, attached proximal to rim of cup between filament bases, yellow, appendages absent; stamens 5; staminodes 0; pistil 2-carpellate, ovary 4-locular, false septa complete and similar to true septa; styles 2, distinct, or connate at base; stigmas capitate, wider than styles. Fruits schizocarps, breaking into 4 nutlets, or indehiscent. Seeds 4, narrowly ovate. x = 6.
Species 1: w United States.