1618 



HY^NANCHE 



HYBRIDS 



HYjENANCHE (Greek, referring to its native African 

 use as a hyena poison). Euphorbiacese. Small tree, 

 sometimes grown in greenhouses. Lvs. whorled or 

 sometimes opposite, simple, entire: fls. dioecious, 

 apetalous, in axillary clusters; sepals in staminate 

 fis. 5-12, stamens numerous: ovules 2 in each of the 

 3-4 cells. The single species is H. capensis, Pers. 

 {Toxicodendron capense, Thunb. H. globosa, Lamb.). 

 Hyena Poison. A much-branched tree, 5-6 ft. high: 

 lvs. hnear to oblong, base cuneate, apex rounded, 

 glabrous: caps, subglobose. S. Afr. It is adapted to 

 well-drained hght soil, and is prop, by cuttings in sand 

 under glass. During its rest-period water should be 

 given sparingly. J. B. S. Norton. 



HYBANTHUS (from Greek meaning hump-backed 

 flower). Violaces. Species about .50, in Old and New 

 World, mostly in tropical and subtropical parts. One 

 species native to the E. U. S., is sometimes hsted: it is 

 an herbaceous perennial 1-2 ft. high, with mostly 

 oblong, narrowly acuminate lvs. 3-5 in. long, and small 

 nodding greenisli fls. soUtary or in pairs in many of the 

 If .-axils: sepals linear and equal; petals mostly nearly 

 equal in length, connivent nearly their entire length, 

 the lower one much larger, saccate at the base, emargi- 

 nate at the broad apex; stamens with broad connec- 

 tives wholly connate into an ovoid sac open only 

 between the free tips, a rounded or 2-lobed scale-like 

 gland adnate to the base anteriorly. 



concolor, Spreng. {lomdiuvi concolor, Benth. & 

 Hook. Sblca concolor, Ging. Cub'cliutn concolor, Raf.). 

 May, June. Moist woods and ravines, Ont. to Ga. and 

 West. F. W. Barclay. 



HYBRIDS are the products of crossing between spe- 

 cies. Of late, the word hybrid has been used by most 

 writers to comprise all crosses, whether between species 

 or varieties. The justification of this usage is the fact 

 that there are no hard and fast hnes between varieties 

 and species, and therefore that hybridism in the old 

 sense is incapable of exact delimitation. The opponents 

 to this usage, however, contend that so long as it is cus- 

 tomary to speak of species and varieties as different 

 classificatory categories, it is equally allowable and use- 

 ful to speak of hybrids as between species and of cross- 

 breeds as between varieties; moreover, historical cus- 

 tom favors this usage. Common-language terms rarely 

 if ever express absolute or ideal truth: they grow up by 

 custom. Whenever now ideas and discoveries render them 

 inexact, it may be quite as well to invent new terms 

 as to give new and technical meanings to old terms 

 which are thoroughly established in literature. The 

 word hybrid has always been a specific term, and it 

 were a pity now to make it a generic one, particularly 

 since there is a well established generic term. The 

 generic word, both substantive and verb, is cross. Specific 

 kinds of crosses are hybrids, between species; cross- 

 breeds, between plants of the same species; half- 

 hybrid, between a species and a variety of another 

 species; bigener, between plants of different genera. 

 There are technical terms to designate the various 

 kinds and degrees of crossing. The word hybrid has 

 now become so flexible, however, and other standards 

 of measurement are so much in vogue, that these special 

 terms are little used. 



It was formerly held that inability to make fertile 

 hybrids is proof that the forms are distinct species; and 

 contrarywise, that plants which make fertile crosses are 

 of one species. Hybridization has also been made a 

 test of genera. These notions are now given up, for 

 crossing and classification belong to two unlike cate- 

 gories of facts. Species and genera are not entities in 

 themselves, but are mere artificial gi'oups made by men 

 for their convenience when writing and speaking of 

 living things. Crossing is a biological phenomenon. 

 Hybrids are unusual facts in nature; that is, they 



are rare compared with the whole number of plants. 

 On the other hand, cross-breeds are usual. Most flow- 

 ers are so constructed as to favor cross-poUination. 

 Cross-breeding is one of the prime means of inducing 

 shght variations and of invigorating a type. Upon the 

 variations which arise from crossing and other means, 

 natural selection operates in the production of new 

 forms. But it is significant that these new forms usu- 

 ally come about slowly and graduaUj'. It is the desire 

 of the cultivator to produce new forms quickly and of 

 pronounced distinctness. He therefore employs cross- 

 ing between unlike types, or species, hoping thereby to 

 secure wider departures. In nature, the cross-breed is 

 the beginning of a process of breeding: it starts off the 

 variation. Man is often tempted to look upon the hybrid 

 as the end. If the products of a given cross are not to 

 his hking, he throws them away and tries again. The 

 most expert plant-breeders, however, now hybridize 

 to get a "break," and thenceforth depend chiefly on 

 selection to realize their clear-cut ideals, particularly 

 in seed-propagated plants. 



To man hybrids are of no value unless they can be 

 propagated. By seeds they usuaUj' vary immensely: it 

 is difficult to ''fix" them so that they wiU come true. 

 By cuttings or layers or division, however, the character 

 of the parent may be propagated with practical cer- 

 tainty: the original plant is divided, and the parts are 

 put on the market. Nearly all commercial hybrids are 

 of plants which are thus propagated by asexual parts: 

 Kieffer pear, hybrid grapes, Wilson blackberry. Wild 

 Goose plum, cannas, roses, begonias, anthuriums, 

 fuchsias, pelargoniums, rhododendrons. Since the 

 hybrid is variable when propagated by seeds, continued 

 selection, or plant-breeding, must be employed to fix 

 and establish a desirable type. 



It is thus seen that hybridization rarely gives rise to 

 dominant horticultural seed-races, but rather to an 

 individual plant which may be disseminated by some 

 divisional means of propagation. The seeds of hybrids 

 — as of the modern cannas — may give rise to good 

 varieties, and they may not; but these new varieties are, 

 in their turn, usually propagated by means of asexual 

 parts if they are to be kept true. 



Practically there is no certainty in hybridization. 

 Rarely can a man picture to himself an ideal variety, 

 and then by means of hybridization produce it. He 

 hybridizes plants which possess some of the character- 

 istics of the desired or ideal variety, and then takes his 

 chances. True plant-breeding sets an ideal, and then 

 reaches it by working along certain definite lines. It 

 seeks first to secure a variation in the desired direction: 

 this may be secured by means of crossing, change of 

 soil, modification of food-supply, and other changed 

 conditions. It seeks, then, to preserve or augment the 

 form by means of definite selection. 



We are not yet able to formulate positive laws of 

 hybridization. Every hybrid is a law unto itself. By 

 the study of many examples of hybridization, one is able 

 to construct an average of probabihties as to what wiU 

 or what will not occm- in a given case: but the given 

 case may contradict all the probabilities without appar- 

 ent cause. Hybridization is an empirical subject. 



One cannot teU what species will or will not hybridize 

 except by trying. Hundreds of species have been tried, 

 and for them the Imowledge is more or less exact. 

 Plants hybridize most freely which are the subjects of 

 much care and coddling: the orchids are the best 

 examples. In these groups, hybrids are chieflj' fanciers' 

 plants, valuable often only because they are hybrids or 

 are rare and curious. One cannot tell beforehand 

 whether the products of any hybridization will be exact 

 intermediates, or in what way or degree they will carry 

 over or blend the parental characters. As a rule, the 

 more closely akin the species, the more perfect will be 

 the blending or amalgamation of the two. See Breed- 

 ing of Plants, Vol. I. 



