92 Order GERANIALES 
Petals over one cm. long, sepals strongly wing-crested. 
5. L. berlandieri. 
1. Linum usitatissimum L. Flax, Linseed. 
Often escapes from cultivation. Broken Bow; Cody; Ponca; Red 
Cloud; Saunders county. 
2. Linum lewisii Pursh. Prairie Flax. 
In the canyons of the Hat Creek basin. Minden; War Bonnet canyon. 
3. Linum sulcatum Riddell. Yellow Flax. 
On dry hills in the eastern part of the state. Bassett; Box Butte; 
Crete; Fairbury; Kearney; Laurel; Lincoln; Long Pine; Valentine. 
4, Linum rigidum Pursh. Large-flowered Yellow Flax. 
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 berlandieri Hook. 
Nebraska, according to Rydberg’s Flora of Colorado. 
5. ZYGOPHYLLACEZ. 
1. Tribulus. 580. 
1. Tribulus terrestris L. Bur-nut. 
Introduced and becoming common. Aurora; Lincoln; Newport; Red 
Cloud. 
6. RUTACEZ. 
Rue Family. ; 
Leaves pinnate. 1. Xanthoxylum. 
Leaves trifoliolate. 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. Hop Tree. 
Thoroughly established and spreading from seed at Hastings. 
7. POLYGALACEZ. 
Milkwort Family. 
1. Polygala. 582. 
Leaves some of them verticillate in 4’s and 5’s. 
Leaves acute; spikes long peduncled. 1. P. verticillata. 
Leaves broader, obtuse; spikes sessile or short pediceled. 
2.-P. crue. 
Leaves all alternate. 
Flowers not white, inflorescence globose, over 8 mm. thick; leaves 
oblong or linear-oblong. 3. P. viridescens. 
Flowers white; leaves entire, their edges revolute. 4. P. alas 
