662 LINACEAE 



1. LINUM L. 



Herbs. Leaves alternate, without stipules. Sepals 5, glabrous, or the inner 

 ones sometimes ciliate. Petals blue or rarely white, unappendaged. Androecium of 

 5 stamens and 5 short staminodia. Styles 5, distinct. Capsule 5-celled and with 

 incomplete partitions, the carpels ridged on the back. Spring and summer. FLAX. 



Inner sepals not ciliate: stigmas slightly longer than broad: perennial native plants. 



Sepals 4-5 mm. long at maturity, less than ^ as long as the capsule. 1. L. pratense. 



Sepals 6-7 mm. long at maturity, over 3^ as long as the capsule. 2. L. Lewisii. 



Inner sepals ciliate: stigmas elongated: annual naturalized plants. 3. L. usitatissimum. 



1. Linum prat&nse (Norton) Small. Stems 1-6 dm. tall: leaves very numerous, 

 approximate, often crowded, relatively short; blades abruptly pointed: capsules 5-6 

 mm. long, over twice as long as the sepals. 



In dry soil, Wyoming to Nevada, Texas and Arizona. 



2. Linum Lewisii Pursh. Stems 2-8 dm. tall: leaves few or rather numerous 

 but not approximate, rather elongated; blades gradually pointed: capsules 4-5 mm. 

 long, less than twice as long as the sepals. 



In dry soil, Alaska to Manitoba, Texas and California. 



3. Linum usitatiseimmn L. Stems 2-9 dm. tall : leaves relatively few, long 

 and thin; blades long pointed: capsules 7-10 mm. long. 



In fields and waste places, southern Canada and the United States. Naturalized from 

 the Old World. 



2. CATHARTOLINUM Reichenb. 



Herbs. Leaves alternate or occasionally opposite, sometimes with stipular 

 glands. Sepals 5, the inner ones at least with gland-tipped teeth. Petals yellow, 

 sometimes pubescent within near the base. Androecium of 5 stamens generally 

 without staminodia. Styles 5, distinct or united. Capsule 5-celled, or completely or 

 incompletely 10-celled by false partitions. 



Styles distinct. 



Staminodia wanting. 



Sepals entire at maturity, the inner ones sometimes erose on account of the bases of the 



deciduous glandular hairs. 

 Stems paniculatcly branched: outer sepals 2-2.5 mm. long at maturity. 



1. C. striatum. 

 Stems corymbosely branched: outer sepals 3-3.5 mm. long at 



maturity. 2. C. Virginianum. 



Sepals, either those of the inner series, or of the outer, or of both 



series, glandular toothed. 

 Capsules spheroidal. 



Outer sepals typically lanceolate; inner sepals abruptly long- 

 pointed. 3. C. medium. 

 Outer sepals typically ovate: inner sepals acute or abruptly 



short-pointed. 4. C. Curtissii. 



Capsules ovoid. 



Outer and inner sepals nearly equal at maturity, shorter 



than the capsule or about equalling it. 5. C. Floridanum. 



Outer sepals much longer than the inner, all surpassing the 



capsule. 6. C. macrosepalum. 



Staminodia present. 



Inflqresence-branches terminating in elongated evenly flowered raceme- 

 like cymes: capsule depressed. 7. C. arenicola. 

 Inflorescence-branches terminating in irregular few-flowered cymes: 



capsule ovoid. 8. C. rupestre. 



Styles more or less united. 



Inner sepals, at least, with glandular-toothed margins, or rarely entire. 

 Sepals persistent: capsules without thickenings at the base. 



Sepals, especially the outer ones, coarsely and irregularly toothed, 



oblong-lanceolate, short-acuminate: capsules ovoid. 9. C. Harperi. 



Sepals, especially the outer ones, finely and regularly toothed, 



narrowly lanceolate, long-acuminate: capsules spheroidal. 10. C. sulcatum. 



Sepals deciduous: capsules with cartilaginous thickenings at the base. 



Inner sepals with wide and very coarsely toothed margins. 11. C. alatum. 



Inner sepals with narrowed finely toothed margins. 



Outer and inner sepals slightly unequal: leaf-blades narrowly 



linear to subulate, 1-ribbed or indistinctly 3-ribbed. 

 Outer sepals with indistinct lateral ribs near the base. 

 Outer sepals lanceolate, 6-7 mm. long, slightly nar- 

 rower than the inner ones. 12. C. Carteri. 

 Outer sepals linear-subulate, 11-14 mm. long, much 



