3292 



SWERTIA 



SYMPHORICARPOS 



greenish yellow, dark-spotted; corolla-segms. mem- 

 branaceous, lanceolate, rather obtuse, pits in 2's, 

 oblong, crested and fringed. S. E. Eu., Caucasus. 



BB. Pits orbicular. 



connata, Schrenk. Perennial: st. erect, many-fld.: 

 Ivs. oblong, acutish, lower attenuate to the petiole; 

 cauline all connate at base: fls. erect, greenish yellow, 

 dark-spotted; corolla punctate, segms. obtuse, apex 

 denticulate; pits distant, very long-ciliate. Siberia. 



perennis, Linn. A hardy perennial J^-l ft. high: 

 lower Ivs. obong-elliptical, long-petioled ; st.-lvs. ovate- 

 oblong, obtuse: fls. mostly 5-merous, blue to white, in a 

 thyrse; corolla-lobes elliptical-oblong, acute, bearing at 

 the base 2 orbicular nectariferous pits crested with a 

 fringe. Colo., Utah, and northward; also in the alpine 

 regions of Eu. and in Asia. S. perennis is an alpine 

 bog-plant and should be given a cool deep moist soil. 



F. W. BARCLAY. 

 F. TRACY HusBARD.f 



SWE2TENIA (named for Gerard van Swieten, 1700- 

 1772). Meliacese. Trees, sometimes grown in the warm- 

 house, one of them yielding the mahogany of commerce : 

 Ivs. even-pinnate, very glabrous; Ifts. opposite, petioled, 

 obliquely ovate, long-acuminate: fls. small, in axillary 

 or subterminal panicles; calyx small, 5-cleft; petals 5, 

 spreading; staminal tube urn-shaped, 10-toothed, 

 anthers 10; disk annular; ovary sessile, ovoid, 5-celled: 

 caps. 5-celled, about 3 in. diam. Three species, Trop. 

 Amer. Intro, into S. U. S. 



Mahagoni, Jacq. MAHOGANY. A large evergreen tree 

 with hard dark red wood of well-known value : Ifts. 6- 

 10: fls. greenish yellow. Tropical regions of N. and S. 

 Amer., W. Indies, and S. Fla. G.C. III. 54:437. 

 According to Mueller, the degree of endurance is not 

 sufficiently ascertained. In Jamaica it hardly reaches 

 an elevation of 2,000 ft. It requires rich soil. It is said 

 that the tree will bloom at small size when grown in pots. 



S. Chlordxylon, Roxbg.=Chloroxylon Swietenia. 



F. W. BARCLAY. 



SYAGRUS: Cocas. 



SYCAMORE in Europe is Acer pseudoplatanus; in 

 America, Platanus occidentalis, although this plant 

 should be called plane-tree. The sycamore of the 

 ancients was a kind of fig known as Pharaoh's fig, Syco- 

 monis antiquorum, or Ficus Sycomorus (for which see 

 pages 1233, 1234, Vol. III). 



SYCOPSIS (Greek, fig and appearance, alluding to 

 its resemblance to certain figs). Hamamelidacese. Five 

 species of evergreen shrubs or trees of China and the 

 Himalayas, with generally oblong, entire or denticulate, 

 stipulate Ivs. and rather insignificant apetalous monoe- 

 cious fls. with minute calyx-lobes in heads or short 

 racemes: stamina te fls. in heads surrounded by pubes- 

 cent bracts; stamens 8, with a rudimentary ovary; pis- 

 tillate fls. with an urceolate calyx inclosing the ovary; 

 styles 2, slender, with decurrent linear stigmas: fr. a 

 dehiscent pubescent caps., with 2 brown lustrous seeds. 

 Only the following species is sometimes cult, for its 

 evergreen foliage ; also the staminate fls. with their rather 

 large red anthers are attractive. It stands the winter 

 with some protection or in a sheltered position at the 

 Arnold Arboretum. Prop, is by seeds or by cuttings of 

 nearly mature wood under glass with slight bottom 

 heat. S. sinensis, Oliver. Shrub or small tree, to 20 ft.: 

 Ivs. short-petioled, elliptic-ovate to elliptic-lanceolate, 

 acuminate, usually denticulate above the middle, gla- 

 brous or sparingly pubescent, 2-4 in. long: pistillate 

 fls. in 6-12-fld. stalked heads; staminate fls. in small 

 heads surrounded by brown pubescent bracts; anthers 

 oblong, red, on slender filaments: caps, densely pubes- 

 cent. Cent, and W. China. H.I. 20:1931; 29:2834, 

 figs - 1 ~ 3 ' ALFRED REHDER. 



SYMBEGONIA (name refers to the union of parts of 

 the flower) . Begonidcese. A few small herbs, all natives 

 of New Guinea (Afr.), differing from Begonia in the 

 tubular female fls.; the male fls. have the parts dis- 

 tinct. <S. fulvo-villosa, Warb., for some time the only 

 known member of the genus, appears to be the only 

 species that has appeared in cult., but is apparently not 

 in the trade: erect herb 8 in. or less high, with red- 

 tinged st. and oblique lance-oblong strongly double- 

 serrate green Ivs. : female fls. pale yellow, with 5 spread- 

 ing serrulate lobes and a 3- winged inferior ovary; male 

 fls. of 2 separate sepals, and 12-20 stamens. B.M. 8409. 



L. H. B. 



SYMBIOSIS is the intimate association of two or 

 more distinct organisms, with benefit to one only, or to 

 both; commensalism ; consort ism; copartnership. In 

 this association each organism is called a symbiont. 



According to the character of the union, several kinds 

 of symbiosis have been recognized: (1) Mutual antago- 

 nistic symbiosis (mutual parasitism), when two organ- 

 isms are foes of each other, as certain bacteria and 

 animals, the latter showing a "natural resistance;" also 

 the syntropism of certain lichens with lichens. (2) Antag- 

 onistic symbiosis (true parasitism), when the host is 

 partly or completely killed by the parasite, as the potato 

 and the rot fungus (Phytophthora infestans}; or galls 

 (hypertrophies) produced on the host, as in the black- 

 knot of plums; and in higher plants, which live at the 

 expense of others, as the mistletoe (green) and the dodder 

 (chlorophylless). (3) Mutual symbiosis, when there is 

 often reciprocal advantage; (a) nutricism, when one 

 symbiont nourishes the other without apparently 

 receiving any return, as the mycorrhiza and the roots of 

 forest trees (mycosymbiosis) ; (6) mutualism, when a 

 mutual benefit results from the union of two organisms 

 capable of living separately, as the bacteroid and the 

 roots of the Leguminosse; (c) individualism, when the 

 symbionts are so intimately connected in their growth 

 as to suggest a single individual, as the union of alga and 

 fungus to form a lichen. By some this relationship of 

 alga and fungus hi the lichen thallus is regarded as 

 helotism, or slavery, where the alga lives entirely indif- 

 ferent to the fungus. The views of Bruce Fink, who con- 

 siders the lichen to be a fungus with an alga associated 

 with it, are widely different from the usually accepted 

 views on the subject. (4) Prototrophy, the wet-nurse 

 relationship, as in the lichen Lecidea intumescens, which 

 eventually gets its nourishment by means of a lodger, a 

 different lichen. (5) Contingent symbiosis, when one 

 symbiont lives in the interior of another for shelter, as 

 Nostoc in the tissues of Hepaticse, Lemna, Cycas, 

 Gunnera; and Anabaena in Azolla. Green plants live 

 symbiotically with animals such as Spongilla, Hydra, 

 and Convqluta. In Hydra, the green alga, known as 

 Chlorella, is found in the endodermic layer and when 

 the colorless eggs of the fresh-water polyp are almost 

 mature a few of the green cells are found migrating into 

 the protoplasm of the egg-cells. 



JOHN W. HARSHBERGER. 



SYMPHORICARPOS (Greek, symphorein, to bear 

 together and karpos, fruit, referring to the clustered 

 fruits). Sometimes spelled Symphoricarpus. Syn., 

 Symphoria. Caprifoliacese. SNOWBERRY. Ornamental 

 shrubs grown chiefly for their attractive fruits. 



Deciduous upright or rarely prostrate shrubs: Ivs. 

 opposite, entire, or on vigorous shoots often sinuately 

 dentate or lobed, exstipulate: fls. short-pedicelled, in 

 terminal or axillary clusters or spikes or sometimes 

 solitary; calyx 4-5-toothed; corolla campanulate or 

 tubular, 45-lobed; stamens 4-5, included or somewhat 

 exserted, style slender with capitate stigma; ovary with 

 2 fertile and 2 sterile cells: fr. a 2-seeded berry. About 

 15 species in N. Amer., south to Mex. and 1 in W. 

 China; many of the American species are closely related 

 and difficult to distinguish. 



