82 GERANIALES 
4. LINACEAE. 
Linum. 578. 
Flowers blue. : 
Flowers less than 2 cm, broad. 1. L. usitatissimum. 
Flowers over 2 cm, wide. 2. L. lewisii. 
Flowers yellow. 
Flowers small, about 12 mm. broad. 3. L. sulcatum. 
Flowers large, 18 mm. or more broad. 
Petals less than one cm. long, sepals not wing-crested. 
4. L. rigidum. 
Petals over one cm. long, sepals strongly wing-crested: 
5. L. arkansanum. 
1. Linum usitatissimum L. Flax; Linseed. 
Often escapes “rom cultivation. Broken Bow; Cody; Ponca; Red 
Cloud; Saunders County. 
2. Linum lewisii Pursh. 
In the canons of the Hat Creek Basin. Minden; War Bonnet Canon. 
3. Linum sulcatum Riddell. “ts, 
On dry hills in the eastern part of the state. "Banactts Box Butte; 
Crete; Fairbury; Kearney; Laurel; Lincoln; Long Pine; Valentine. 
4. Linum rigidum Pursb. 
Common in dry soil in the western part of the state. Anselmo; Box 
Butte County; Dismal River; Hat Creek Basin; Kearney; Mullen; 
Pine Ridge; Ponca; St. Helena; Thedford; Valentine, 
5. Linum arkansanum Osterh. 
Nebraska according to Rydberg’s Flora of Calorado. 
5. ZYGOPHYLLACEAE. 
Tribulus. 580. 
1. Tribulus terrestris L. 
Introduced but local. Aurora; Newport; Lincoln; Red Cloud. 
6. RUTACEAE, 
Leaves pinnate. 1. Xanthoxylum. 
Leaves trifoliate, 2. Ptelea. 
1. Xanthoxylum. 581. 
1. Xanthoxylum americanum Mill. Prickly ash. 
Mostly along streams in the eastern part of the state. Ashland; Guide 
Rock; Long Pine; Milford; Nebraska City; Ponca; Royal; Rulo; 
‘Weeping Water. 
2. Ptelea. 581, 
1. Ptelea trifoliata L. 
Thoroughly established and spreading from seed at Hastings, 
7. POLYGALACEAE, 
Polygala. 582. 
Leaves some of them verticillate in 4’s and 5’s. 1. P. verticillata. 
