FLOWERING PLANTS AND FERNS OF ARIZONA 513 



peduncled; petals yellow; fruits flat, of 5 nutlets, each dorsally armed 

 with 2 strong spines and containing 2 or more seeds separated by 

 transverse partitions. 



1. Tribulus terrestris L., Sp. PL 387. 1753. 



Here and there throughout the State, 5,000 feet or lower, often very 

 abundant at roadsides and in fields, flowering in summer. Extensively 

 naturalized in the United States, from southern Europe. 



Plant now commonly known as puncturevine, also as bullhead and 

 burnut. A troublesome annual weed because of the numerous spiny 

 fruits each plant produces. Although the plants produce seeds in 

 great quantities, and the fruits are readily disseminated by means of 

 furred animals and automobile tires, the weed is easily controlled by 

 cultivation. The spines of the fruit are incapable of puncturing serv- 

 iceable automobile tires but do penetrate bicycle tires. A single 

 carpel somewhat resembles the head of a bull. Hay containing the 

 fruits may cause troublesome sores in the mouths of livestock. 



4. KALLSTROEMIA 



Plants very similar to Tribulus but the fruit more convex, breaking 

 up at maturity into 8 to 12 nutlets, these 1 -seeded and merely tuber- 

 culate on the back. 



Key to the species 



1. Petals 15 to 30 mm. long, orange; sepals 8 to 15 mm. long; beaks of the mature 

 fruit slender, slightly conic at base, 8 to 11 mm. long, much longer than 

 the nutlets (usually at least twice as long) ; leaflets up to 25 mm. long; stems 



hirsute-hispid, also usually copiously short-pilose 1. K. grandiflora. 



1. Petals not more and usually less than 12 mm. long, orange yellow, often fading 



whitish; sepals less than 8 mm. long; beaks of the fruit stout, strongly conic 



at base; leaflets seldom more than 15 mm. long (2). 



2. Beaks of the mature fruit 4 to 6 mm. long, commonly longer than the nutlets; 



petals 6 to 12 mm. long; sepals persistent until after maturity of the 



fruit; nutlets usually prominently tuberculate on the back. 



2. K. PARVIFLORA. 



2. Beaks of the fruit not more than 3 mm. long, shorter than the nutlets; petals 

 not more than 6 mm. long (3). 

 3. Plant conspicuously hirsute, many of the hairs long and spreading; sepals 

 persistent; beaks of the fruit copiously strigose-pubescent; nutlets 

 with low, transversely elongate (ridgelike) tubercles. 



3. K. HIRSUTISSIMA. 



3. Plant not conspicuously hirsute, most of the hairs appressed; sepals usually 

 deciduous before maturity of the fruit; beaks of the fruit glabrous or 

 nearly so 4. K. californica. 



1. Kallstroemia grandiflora Torr. in A. Gray, PL Wright. 1: 28. 1852. 



Greenlee County to Yavapai County, south to Cochise, Santa Cruz, 

 and Pima Counties, 5,000 feet or lower, common on open plains and 

 mesas, February to September. Texas to Arizona and Mexico. 



This plant, often locally known as Arizona-poppy, is one of the 

 most attractive summer annuals in the southern part of the State. 

 The large flowers, rich orange in color, superficially resemble those 

 of the California-poppy (Eschscholtzia) . There is remarkable vari- 

 ation in size and shape of the anthers, apparently uncorrelated 

 with other characters. The anthers are usually nearly orbicular 

 and 1 to 2 mm. in diameter, but in specimens collected at San Ber- 

 nardino ranch, Cochise County {Mearns 1982), they are elliptic and 

 up to 4 mm. long. 



