OPUNTIACEAE 811 



3. Nuttallia stricta (Osterhout) Greene. Steins corymbose above: leaf- 

 blades sinuate-pinnatifid, the teeth broad, obtuse: petals ochroleucous or straw-colored, 

 gradually pointed: capsules stout. 



In dry or stony soil, South Dakota to Nebraska, Colorado and Texas. 



3. EUCNIDE Zucc. 



Herbs with stinging and barbed hairs. Leaf -blades broad, toothed and shal- 

 lowly lobed. Flowers in raceme-like cymes or solitary. Petals broad. Anthers with 

 unappendaged connectives. Style elongated. Stigma minute. Ovules or seeds 

 numerous. 



1. Eucnide bartonioides Zucc. Stem and branches spreading or decumbent, 1-4 

 dm. long: leaf -blades 3-8 cm. in diameter: hypanthium bristly-hirsute: sepals lan- 

 ceolate to linear-lanceolate: petals yellow, 2-4 cm. long: capsules turbinate, 1.5-2 

 cm. long. 



In dry soil, Texas, New Mexico and adjacent Mexico. Spring and summer. 



4. CEVALLIA Lag. 



Herbs with pale stinging hairs. Leaf-blades relatively narrow, pinnatifid. 

 Flowers capitate. Petals narrow. Anthers with long appendaged connectives. Style 

 short: stigma ovoid. Ovule and seed solitary. 



1. Cevallia sinuata Lag. Stems 1-8 dm. tall : leaf -blades 2-8 cm. long, 

 tomentose beneath: heads plumose: sepals linear: petals linear, 7-9 mm. long: cap- 

 sules about 5 mm. long. 



In dry soil, Texas, New Mexico and adjacent Mexico. Spring and summer. 



FAMILY 2. OPUNTIACEAE H.B.K. CACTUS FAMILY. 



Succulent shrubby plants, usually copiously furnished with spines, which 

 arise from cushions of small or minute bristles (areolae). Leaves usually want- 

 ing. Stems depressed, globose, columnar and terete or angled, or flattened and 

 jointed or continuous. Inflorescence often axillary or lateral. Flowers usually 

 large and showy, perfect, solitary. Calyx of few or numerous imbricated sepals, 

 the inner series petal-like. Corolla of numerous petals in 2 or many series. 

 Androecium of numerous stamens in several series. Filaments filiform, some- 

 times cohering with the base of the petals. Anthers introrse. Gynoecium of 

 several united carpels. Ovary inferior, 1-celled, with several parietal placentae. 

 Styles united, terminal, simple, elongated or pyramidal. Stigmas of the same 

 number as the placentae, variable in shape. Ovules numerous, anatropous, 

 horizontal. Fruit a fleshy berry, or rarely dry, smooth or more or less spiny. 

 Seeds numerous, shining or tubercled, often with a dark more or less furrowed 

 testa. Embryo curved, or thick, fleshy and rounded, in scant or copious endo- 

 sperm. [Cactaceae Lindl.] 



Plants little, if at all, jointed: leaves none or obsolete: areolae without bristles. 

 Plants globose to oval. 



Flowers borne between the tubercles. 1. CACTUS. 



Flowers borne on the tubercles. 2. ECHINOCACTUS. 



Plants cylindric or prismatic. 



Style green: plants with low short stems: flowers rotate or short- 



campanulate. 3. ECHINOCEREUS. 



Style white or yellow: plants with elongated stems and branches: 



flowers campanulate. 

 Plants prostrate, reclining or climbing. 



Stem and branches with few shallow grooves: fruit spiny. 4. WILCOXIA. 



Stem and branches 3-5-angled: flowers nocturnal: fruit scaly 



or spinv. 



Plants with aerial roots: berry scaly. 5. HYI.OCEREUS. 



Plants without aerial roots: berry spiny. 6. ACANTHOCEREUS. 



Plants erect, the stem and branches columnar, grooved. 



Style exserted: berry smooth: flowers short-campanulate: 



perianth green-purple. 7. CEPHALOCEREUS. 



Style included: berry scaly: flowers long-campanulate: peri- 

 anth white. 8. HARRISIA. 

 Plants conspicuously jointed: leaves present on the young joints: areolae 



with barbed bristles. 9. OPUNTIA. 



