630 FLORA. 



2 mm. wide, obtuse; flowers sessile, minute; capsule nearly as in the preceding; 

 seeds short-oblong, nearly straight, about 0.5 mm. long. Margins of ponds, 111. 

 and Cal. Summer. 



3. Elatine triandra Schk. LONG-STEMMED WATER-WORT. (I. F. f. 2468.) 

 Flaccid, tufted, immersed or creeping; stems 5-10 cm. long. Leaves oblong or 

 oblanceolate, very thin, obtuse, 48 mm. long, narrowed at the base; flowers 

 minute, sessile; sepals commonly 2; petals, stamens and stigmas 3; seeds slightly 

 curved, about the size of those of E. Americana. Ponds, 111., S. Dak. and Neb. 

 Also in Europe. Summer. 



2. BERGIA L. 



Herbs, or somewhat shrubby plants, more or less pubescent, with opposite 

 leaves and small lowers. Parts of the flower in 5's (very rarely in 4*3 or 3's). Pod 

 crustaceous, 5-valved. Seeds numerous, striate longitudinally and transversely. 

 [In honor of Dr. P. J. Bergius, 1723-1790, professor of Natural History in Stock- 

 holm.] About 15 species, natives of warm and temperate regions. 



i. Bergia Texana (Hook.) Seub. TEXAS BERGIA. (I. F. f. 2469.) Pros- 

 trate or ascending, diffusely branched ; stems 1.5-2.5 dm. long. Leaves spatulate 

 or obovate, 2-4 cm. long, serrate, narrowed into a short petiole; stipules about 

 2 mm. long, ciliate-serrulate; flowers short- peduncled, about 3 mm. broad, solitary 

 or 2-3 together in the axils; sepals ovate, acuminate, denticulate, slightly longer 

 than the obtuse petals; capsule globose, 2 mm. in diameter, its dehiscence septi- 

 fragal; seeds oblong, striate longitudinally and cross-barred. Southern 111. to Tex., 

 Nev. and Cal. Summer. 



Family 4. CISTACEAE Lindl. 

 Rock-rose family. 



Shrubs or low woody herbs, with simple leaves, and solitary racemose 

 or paniculate flowers. Flowers regular, generally perfect. Sepals 3-5, 

 persistent, when 5 the 2 exterior ones smaller, the 3 inner convolute. 

 Petals 5 or 3, or wanting, fugacious or persistent. Stamens oo , hypogy- 

 nous. Ovary i, sessile, i-several-celled ; ovules orthotropous, stalked ; 

 stvle simple. Capsule dehiscent by valves. Seeds several or numerous ; 

 embryo slender ; endosperm starchy or fleshy. Four genera and about 

 160 species, all but i or 2 natives of the northern hemisphere. 



Petals 5, yellow, fugacious, or wanting. 



Leaves broad, lanceolate or oblong. i. Helianthemum. 



Leaves subulate or scale-like, imbricated ; style long. 2. Hudsonia. 



Petals 3, not yellow, persistent; flowers minute; style none. 3. Lechea. 



x. HELIANTHEMUM Pers. 



Woody herbs or low shrubs, more or less branching, mostly with showy yel- 

 1 >w flowers, and sometimes (in the following species) with other smaller apetalous 

 ones. Petals in the larger flowers large, fugacious. Stamens numerous. Placentae 

 or false septa 3. Ovules few or oo ; style jointed with the ovary; stigma capitate 

 or 3-lobed. Embryo curved. [Greek, sun-flower.] About 125 species, of wide 

 distribution. Besides the following, about 8 others occur in the Southern States 

 and on the Pacific Coast. 



Petaliferous flowers solitary, few or several: apetalous flowers in axillary sessile clusters. 

 Petaliferous flowers 5-12, in a short terminal cymose raceme, their capsules 3-4 mm. 

 long, little, if at all, overtopped by the short later axillary branches; capsules of 

 the apetalous flowers about i mm. in diameter. i. H. maj'us. 



Petaliferous flowers solitary, rarely 2, their capsules 6-8 mm. long, much overtopped 

 by the later elongated axillary branches ; capsules of the apetalous flowers nearly 

 4 mm. in diameter. 2. H. Canadense. 



Flowers all cymose at the summit of the stem, the petaliferous ones slender-pedicelled. 



3. H. corymbosum. 



i. Helianthemum majus (L.) B.S.P. HOARY FROSTWEED. (I. F. f. 2470.) 

 Hoary-canescent, erect, 3-6 dm. high. Leaves oblong-lanceolate or oblanceolate, 



