510 MISC. PUBLICATION 423, U. S. DEPT. OF AGRICULTURE 



Specimens collected in Santa Cruz County {Peebles et al. 4656, 

 5612) differ from Trelease's description in having the sepals acutish 

 instead of "very obtuse" and in having 2, not 4 callosities, these 

 sometimes deeply lobed at base. 



57. LINACEAE. Flax family 

 1. LINUM. Flax 



Plants herbaceous, annual or perennial; stems slender, commonly 

 erect and branched; leaves simple, sessile, mostly alternate; inflores- 

 cence cymose-paniculate or racemose; flowers regular, perfect; sepals 

 and petals 5, the sepals persistent, the petals deciduous, blue or yellow; 

 stamens 5, sometimes with 5 additional rudiments, the filaments 

 united below; fruit a 5- or 10-valved capsule. 



The outstanding species, of Old World origin, is flax (L. usitatis- 

 simum L.), from the stem fibers of which linen, and from the seeds 

 linseed oil, are manufactured. One of Arizona's yellow-flowered 

 species, L. neomexicanum, is reported to be poisonous to horses and 

 sheep. Cyanogen is thought to be the toxic constituent. 



Key to the species 



1. Petals sky blue, 1 to 2 cm. long; sepals glandless; stigmas introrse, slightly 



longer than thick; plant perennial 1. L. lewisii. 



1. Petals yellow or orange; sepals, at least the inner ones, bearing marginal glands; 

 stigmas terminal, capitate (2). 

 2. Styles separate to the base; sepals not or scarcely aristate, the outer ones 

 entire or with few glandular teeth (3). 

 3. Inflorescence elongate, narrow, interrupted-racemiform; plant annual or 

 biennial ; outer sepals lanceolate or oblong-lanceolate ; stems erect, the 

 branches ascending at a narrow angle; capsule subglobose-ovoid. 



2. L. NEOMEXICANUM. 



3. Inflorescence short, fastigiate, corymbiform or compact-racemif orm ; 



plants perennial; outer sepals ovate 3. L. kingii. 



2. Styles united nearly to the apex; sepals spinose-aristate, the outer ones with 

 numerous glandular teeth; plants mostly annual (4). 



4. Pedicels and stems densely puberulent; angles of the stem not winged; 



stems usually branching from near the base, the branches loosely 



spreading 4. L. puberulum. 



4. Pedicels and stems glabrous, or sparsely and obscurely puberulent; angles 

 of the stem narro wly winged 5. L. aristatum. 



1. Linum lewisii Pursh, Fl. Amer. Sept. 210. 1814. 



Apache County to Mohave County, south to Cochise and Pima 

 Coimties, 3,500 to 9,500 feet, common on open mesas and in conifer- 

 ous forests, March to September. Saskatchewan and Alaska to 

 northern Mexico. 



This handsome plant closely resembles cultivated flax but is peren- 

 nial. Occasional specimens have nearly white flowers. It is stated 

 that the Indians in some of the Western States used the long fibers of 

 the stems for making cordage. 



2. Linum neomexicanum Greene, Bot. Gaz. 6: 183. 1881. 



Cathartolinum neomexicanum Small, North Amer. Fl. 25: 73. 

 1907. 



Coconino County and Hualpai Mountain (Mobave County), south 

 to Cochise and Pima Counties, 6,000 to 8,000 feet, common in yellow 



