Helianthemum, CISTACEiE. 77 



1. HELIANTHEMUM. Tourn. insL t. 128 ; Endl. gen. 5029. rock-rose. 



[Named from the Greek, helios, the sun, and anthemon, a flower ; the flowers opening in the sunshine.] 



The two exterior sepals usually much smaller and bract-like, or wanting. Petals 5, or rarely 

 3, sometimes abortive, fugacious. Stigmas 3, large, fimbriolate, more or less united into 

 one. Capsule triangular, 3-valved, few- or many-seeded : placentae filiform, in the axis of 

 the valves or on imperfect dissepiments more or less projecting into the cell. Embryo 

 inflexed. 



The North American species of this genus produce two sorts of flowers, often on the same specimen: 1. Terminal or 

 dichotomal flowers, usually preceding the others, on slender peduncles, with conspicuous petals and numerous stamens : 

 2. Smaller flowers, mostly clustered in axillary cymes or glomerules, scarcely ever fully expanding, with the petals minute 

 or often wanting, fewer stamens, and smaller fewer-seeded capsules. Sometimes the latter only are produced, 



1. Helianthemum Canadense, Michx. Frost-weed. Frost-wort. 



Stem at first simple, erect or ascending ; the primary or terminal large and petaliferous 

 flowers few or solitary, on peduncles about the length of the flower, the erosely emarginate 

 petals about twice the length of the calyx ; secondary flowers axillary, very small, nearly 

 sessile, solitary or somewhat clustered on short leafy branches, the petals very small or none, 

 and the outer sepals usually wanting ; leaves oblong, or somewhat lanceolate, with revolute 

 margins (when dry), and, as well as the sepals and often the branches and peduncles, canes- 

 cently tomentose. — Michx. fl. \. p. 308 ; Pursh, fl. 2. p. 363 ; Ell. sk. 2. p. 4 ; Hook, 

 ft. Bor.-Am. l.p.72; Darlingt. fl. Cest. p. 313 ; Torr. ^ Gr. fl. N. Am. 1. p. 151. H. 

 ramuliflorum, Michx. I. c. ; Pursh, I. c. ; Ell. I. a. H. corymbosum, Pursh, I. c. H. ros- 

 marinifolium, Pursh, I.e. Cistus Canadensis, Linn.; Bigel. fl. Bost. p. 212. Lechea 

 major (the apetalous state), Linn. aman. acad. 3. p. 11. 



Stem about a foot high, rigid, at length branching ; the branches flexuous, purplish. Leaves 

 about an inch long and 3-4 lines wide, the pubescence stellate and fasciculate. Primary 

 flowers nearly an inch in diameter. Exterior sepals narrow and linear ; the three interior 

 ones ovate with an abrupt point. Petals obovate, yellow. Secondary flowers sometimes very 

 numerous, their capsules not larger than a large pin's head. Capsules of the primary flowers 

 3-4 lines long, ovate, shining. Seeds somewhat triangular, rough with minute points. 



Dry sandy woods and hill-sides. Primary flowers appearing in June, the others throughout 

 the season. — The plant is sometimes employed as an astringent and tonic. It received its 

 popular name from the circumstance of its shooting out, early in the winter, small icy crystals 

 from the cracked bark near the root. A similar phenomenon has been noticed in several other 

 plants, but has not yet been satisfactorily accounted for.* 



 See an article by Sir J. F. W. Herschel, on this subject, in the Philosophical Magazine, 3rd ser. vol. 2. p. 110. 



