150 LOASALES 
1. Opuntia humifusa Raf. Western Prickly-Pear. 
Opuntia mesacantha Raf. 
Common ‘in dry soil in the northwestern part of the state. Belmont; 
Cherry County; Long Pine; Pine Ridge; Thomas County; Wilsonville. 
2. Opuntia tortispina Englem. 
Nebraska according to Britton’s Manual. 
3. Opuntia polyacantha Haw. F 
In dry prairies mostly in the western part of the state. Alliance; Bel- 
mont; Cherry County; Grand Island; Holdrege; Phelps County; Pine 
Ridge; Plummer Ford; Thedford. 
4. Opuntia rhodantha K. Sch. . 
Nebraska according to Rydberg’s Flora of Colorado. 
5. Opuntia fragilis (Nutt.) Haw. 
In dry soil in the northern and western parts of the state. Cherry 
County; Deuel County; Sheridan County; Valentine. 
LOASALES, 
Erect herbs; flowers perfect; stamens numerous. 1. Loasaceae. 
Climbing or prostrate vines; flowers monoecious or dioecious; sta- 
mens not more than three. 2. Cucurbitaceae. 
1. LOASACEAE. 
Mentzelia. 641. 
Flowers not over 2 cm. broad, petals 5, filaments 20-40, capsule linear. 
Stems very rough, calyx lobes 6 mm. long, capsule 6-12 seeded. 
M. oligosperma. 
Stems nearly smooth, calyx lobes 4 mm. long, seeds numerous. 
2. M. albicaulis. 
Flowers 3-10 cm. broad, petals 5 or 10, filaments 100 or more, capsule 
oblong. 
Flowers 3-5 cm. broad, petals 10, capsule 1.5-2.5 cm. long. 1. M. nuda. 
Flowers 7-10 cm. broad, capsules 2.5-3 cm. long. 
Flowers yellowish-white, opening in the evening, petals 10, calyx 
tube bracted. 3. M. decapetala. 
Flowers bright yellow, opening in the sunshine, petals 5, or if 
10 the inner narrower, capsules bractless. 4. M. laevicaulis. 
1. Mentzelia nuda (Pursh) T. & G. 
Dry prairies in the western part of the state. Alliance; Belmont; Dis- 
mal River Pine Ridge; Scitts Bluff; Turner Creek; Deuel County. 
2. Mentzelia albicaulis Dougl. 
Scotts Bluff. 
3. Mentzelia decapetala (Pursh.) Urban & Gilg. 
Dry prairies mostly in the western and northern parts of the state. 
Chadron; Franklin; Grand Rapids; Hat Creek Basin; Niobrara; Pine 
Ridge; Red Cloud; Scotts Bluff County. 
4. Mentzelia laevocaulis (Dougl.) T. & G. 
Box Butte County. 
