1654 



SELF -STERILITY 



ther develop any tendency towards self-sterility and 

 separation of the sexes which the parent plant may 

 possess. 



(3) The careless practice of taking cions promiscu- 

 ously from the nursery row and from unreliable 

 sources may perpetuate self-sterile individuals. 



(4) Breeding and selecting for other qualities than 

 those associated with seed production may tend to favor 

 these qualities at the expense of the latter. 



(5) Crossing and intercrossing of hybrids may tend to 

 modify the reproductive organs and to produce self- 

 sterility. 



(6) Excessive cultivation and over-feeding with ni- 

 trogenous fertilizers may induce too vigorous wood- 

 growth at the expense of seed and fruit production. 



Self-sterile varieties are unable to fruit and produce 

 seed when planted by themselves. When such varieties 

 are desired for planting they should always be planted 

 with other varieties whose time of flowering is the same. 

 Self-sterility is not always complete. There are all in- 

 termediate grades between plants that are wholly self- 

 sterile and those that are self-fertile. 



For a condensed list of the important varieties of 

 leading fruits which are known to be self-sterile or 

 self-fertile, see Bailey's "Principles of Fruit-Growing," 

 3d edition, pp. 229, 230, and "The Pollination of Pear 

 Flowers," by M. B. Waite, Bulletin 6, Div. of Veg. 

 Path., U. S. Dept. Agric. A full and popular treat- 

 ment of the whole problem as it affects fruit-growers 

 will be found in Bulletin 181, Cornell Exp. Sta., 

 by S. W. Fletcher. For the self-sterility of grapes, 

 see Bulletin 169, N. Y. Exp. Sta., by S. A. Beach. For 

 plums, see the writings of F. A. Waugh. See Pollina- 

 tion. E. P. SANDSTEN. 



SELlNUM (derivation doubtful). Umltelliferce. About 

 25 species of rather large perennial herbs, mostly from 

 the northern hemisphere, with pinnately decompound 

 Ivs. and compound radiate umbels of small white or 

 rarely yellowish white flowers: petals obovate-emargi- 

 nate: fr. ovoid or nearly quadrate. 



tenuifdlium, Wall (Oredcome Oandbllei, Edgew. ). A 

 hardy perennial with finely cut fern-like foliage and 

 stem often 8 ft. high, branched, with numerous umbels 

 of white fls. : ultimate segments of Ivs. narrowly lance- 

 olate, acute: fr. 2-3 lines long, much compressed dor- 

 sally, four to six times as broad as thick; lateral ridges 

 much the broadest. India. Gn. 38, p. 221. Offered as 

 a novelty in America in 1899 and recommended as a 

 foliage plant for single lawn specimens. 



F. W. BARCLAY. 



SEMECAKPUS (Greek, mark and fruit; referring to 

 use of fruit juice). Anacardid,cece. A genus of 20 spe- 

 cies of tropical Asiatic and Australian trees with simple, 

 leathery Ivs. and small fls. in branching panicles : drupe 

 fleshy, oblong or nearly globose, 1 -seeded. 



Anacardium, Linn. f. MARKING-NUT TREE. A moderate- 

 sized deciduous tree with large, oblong or obovate-oblong 

 Ivs. 8-24 in. long by 5-10 in. wide: fls. greenish white, % 

 in. across, nearly sessile, in stout branching panicles 

 about the same length as the Ivs.: drupe 1 in. long, 

 smooth, black. India. The black acid juice of the nut 

 is used for printing cotton cloth. Cult, in S. Fla. 



E. N. REASONER and F. W. BARCLAY. 



SEMELE( mother of Bacchus). Lilibcece. The CLIMB- 

 ING BUTCHER'S BROOM is a tender evergreen vine 

 which attains a height of 50-60 ft. and is remarkable 

 for bearing its flowers on the margins of the " leaves " 

 instead of on separate flower-stalks. These fls. are 

 small, yellow, 6-lobed blossoms about three-eighths of 

 an inch across. What appear to be leaves are techni- 

 cally "cladophylla," i. e., leaf -like branches. They are 

 organs which have the form and function of leaves but 

 not the morphology. Semele belongs to the small group 

 of 4 genera known as the Asparagus tribe, all the mem- 

 bers of which have cladophylla. Semele differs from 

 the Butcher's Broom (Ruscus) in having 6 anthers in- 

 stead of 3 and in having the tts. borne on the margin of 

 the cladophylla instead of along the midrib. Aspara- 

 gus differs from both in having the fls. not borne on 



SEMPERVIVUM 



the cladophylla and the filaments free instead of grown 

 into an urn-shaped body. 



Semele is a genus of one species, a native of the 

 Canary Islands. The plant is not known to be cult, in 

 American greenhouses, but it is suitable for outdoor 

 cultivation in the South. Franceschi (Santa Barbara) 

 says it looks like a gigantic smilax and has dark green, 

 tropical foliage likely to be mistaken for some of the 

 Indian climbing palms. 



andr6gyna, Kunth. Scandent, branching: cladodia 

 ovate or ovate-lanceolate, acuminate, leathery: fls. small, 

 yellow, clustered: ovary 3-loculed: berry globose, inde- 

 hiscent. B.M. 1898 and 3029 (as Ruscns androgynus). 

 R.H. 1894, p. 546. G.M. 31:477, 479; 37: 261. -The 

 members which have the position of leaves are mi- 

 nute scales, in the axil of which are borne the clado- 

 phylla, the latter being 3-4 in. long. -^y jj 



SEMPERViVUM ( Latin, living forever). Crassuldceoe. 

 HOUSELEEK. About 40 species of fleshy herbs widely 

 scattered in the mountainous countries of the Old 

 World. They are mostly hardy perennials and stemless, 

 and increase by rosettes (Fig. 2310) which are sent out 

 from the parent plant, thereby suggesting the popular 

 name "Hen-and-chickens." The Ivs. are thick, short 

 and succulent. The fls., which are borne in panicled 

 cymes, are mostly yellow, greenish yellow, or some 

 shade of rose or purple, rarely white. The individual 

 fls. are larger than those of Sedum, but the clusters are 

 less showy. Houseleeks are cultivated more for foliage 

 than for flowers. They are not used for as great a va- 

 riety of purposes as Sedums, but they are popular for 

 carpet bedding, rockwork and covering dry banks and 

 bare sandy wastes. They are of the easiest culture and 

 are quickly multiplied by means of the offsets or ro- 

 settes. They may be used alone for permanent carpet 

 beds, and for this special purpose are preferable to the 

 more popular but tender Echeveria. The foliage re- 

 mains green all winter. The Ivs. are often spotted with 

 red toward the tip, and this color is brighter if the plants 

 have full sunlight. The names "Houseleek" and "Hen- 

 and-chickens " are loosely applied to the whole genus. 

 If these names are to be restricted, the former should be 

 used for Sempervivum tectorum and the latter for S. 

 globiferum. The common species, which grows on the 

 roofs of houses in Europe, is S. tectorum. In the case 

 of S. globiferum the young rosettes are attached to the 

 parent plant by a more slender thread than usual and 



2310. Rosette and offsets of a Houseleek Sempervivum 

 tectorum (X %). 



more easily detach themselves and roll about. The 

 spider-web species are the prettiest of them all, by reason 

 of the webs that cover the young rosettes. These webs 

 are made by the plants themselves and are incidental to 

 development. 



Sempervivum is closely related to Sedum, but the 

 floral parts are multiples of 6 or some larger number, 

 while the floral parts of Sedum are in 5's. The genus 

 is a difficult one for the botanist. It has been mono- 

 graphed by J. G. Baker in "Gardener's Chronicle" for 



