HYDRANGEA 



783 



i,i_ iiioii belong to two uulike categoiiis of 



ti, . - in.l genera are not entities in tliem- 



s,;., ..re artificial groups made by men for 



the u . jii , viLi- III L- when writing anil 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-pollination. 

 Cross-breeding is one of the prime means of inducing 

 slight variations and of invigorating a type. Upon the 

 variations which arise from crossing and other means, 

 natural selection oper.ites in the production of new 

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

 ally come about slowly and gradually. 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 Hy- 

 brid as the end. If the products ct' a -ivcn cross are 

 not to his liking, he throws tli. )n ^.w^n ^ni<l tries again. 

 The most expert plant-breeds i-. Iimw.m r. ii.w hybridize 

 to get a "break, "and thence fort li .l.-i" ih1 .•hietiy on selec- 

 tion 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 usually vary immensely: it 

 is difficult to "fix" them so that they will 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 cunimer.'ial Hybrids are 



of plants Hi' )'-li :m--' lilil- |.r..|M'j:n.-.l In :.-r.su:il |.:n'ts: 



Kieffer i.-:ii II -i': ■ ■ ■ • '■• ■: i^ -i- • ' ■ " ''Vild 



Goose pi ■ ■ < ■ • '■\'- 



sias, pel;ii'i;"n:uiii.. i-|i-il"'l-i..|ri .11 ~ , >n..'-iIm^ llMn'id 

 is variable when propagated by seeils, contiiiued selec- 

 tion, or plant-breeding, must be employed to fix and es- 

 tablish a desirable type. 



It is thus seen that hybridization rarely gives rise to 

 dominant horticultural seed-races, but rather to an iii- 

 dividual plant which may be disseminated by some di- 

 visional means of propagation. The seeds of Hybrids — 

 as of the modem cannas— may give rise to good varie- 

 ties, 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 con- 

 ditions. It seeks, then, to preserve or augment the form 

 by means of definite selection. 



Fundamentally, there are no 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 i.nii)abiUties as Ut \\\r.,t will or what will not 

 occur in ;i ifivcii cas,. : but thr -iyni ra-,c may contradict 

 all the pr"l'aiiilitirs wirlMiiit ai>|ianni caiisr. Hybridiza- 



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 Pollina- 

 tion. 



The literature of hybridization is extensive but scat- 

 tered. The standard text is Focke's" Die Pflanzen-Misch- 

 linge," 1881. The possibilities of hybridization as a factor 

 in plant-breeding are presented in many aspects in 

 • the "Hybrid Conference Report " of the Royal Horticul- 

 tural Society, London, 1900. There are special books de- 

 voted to orchid Hybrids (see Orchids). In North America 

 there has been little fundamental writing on the subject. 

 See an excellent paper by Swingle and Webber, Year- 

 Book of theU. S. Dept. Agric. 1897; papers in Ameri- 

 can Gardening, 1899, pp. 397, 413, 431 ; Bailey's "Plant- 

 Breeding," 1895. L. H. B. 



irtize 



except by trying. Hundreds .if s,i,.,.i,.. have 1 n tried, 



.and for them the knowledL'e is luoi-.- ..r 1.-. .xact. 

 Plants hybridize most freely wliiel, are tl,.- subjects of 

 much care and coddling: the orchids are the best ex- 

 amples. In these groups, Hybrids are chiefly fanciers' 

 plants, valuable often only because they are Hybrids or 

 are rare and curious. One cannot tell beforehand 



50 



HYDRANGEA (Greek. Inidn 

 vessel ; alluding to the cup-^li: 



site, simple, rarely l..bcil. |icti.ili 

 bluish or pinkish tis ii r\ 11 



usually mar:: 

 pals, or in sn 

 larged : fr. : 

 lata is the ha 

 and M. Bretscl 



nnd aqgeion, 

 . S„.ri'fragd- 



siuall. white, 

 panicles, bearing 



. with enlarged 



the fls. are sterile ami en- 

 icant capsule. M.panicu- 



11 . arborescens, H. radiata 

 almost hardy North, 



while H. qnercifolia and petinlaris require at least 

 very sheltered position and IT. hortensis, velutina, in- 

 volucrata and virens are still more tender, and can hardly 

 be grown outdoors North except when well protected and 

 sheltered. They grow best in a rich, porous and some- 

 what moist soil and thrive well in partly shaded posi- 

 tions, but flower more freely in full sun if they only have 

 sufhcient moisture. All Hydr.'infejis are well adapted 

 for borders of shrubberies. :iiid //. iiam, ulula and hor- 

 tensis, es'peciB.Wj thi; varieties \Mili si, file lis., lire very 

 showy as single speciniiiis .m tlie 1.,\mi. Iu warmer cli- 

 mates the latter is sometiiiies u^e.l f..r ornamental 

 hedges (see G.C. III. 24:337 ami 4.1(1); but it is not 

 hardy in the North. These and also most of the 

 other species should be pruned in fall or early spring, 

 and the branches of the previous year cut back to 1-3 

 pairs of buds, accrdiue to the i;routl. of the branches 

 anfl the desirid size ef the {.auicle^; if onl 

 pruned the panicles will be luanx but small, S 

 they are cut back every year aluiest t.. the gr 

 produce then enormous panii'les. wliicli, li..we 

 ally need artificial sui>i>ort and Lack tiie irracel 

 less severely pinneil ].lants. //. i„t HimhtUi . 1 

 diflora can be L-mwi, in a small standard tree 



planted in 

 strongest s 

 height of 4- 

 the sumnie 

 cut off, and 



ightly 



, and cut down to the base. The 

 e.acli |,l.nit will attain by fall the 

 reely mainired and watered during 

 iimu, all the weaker branches are 

 er climates the plants should be 

 lifted and steied in :i frost-proof pit or cellar, since the 

 wood is ni,r Usually sufiiciently ripened to withstand 

 sever.- fro-f. In tin- following year the top of the stem 

 is allowed to liraiicli. The weaker basal shoots may be 

 pegL'ed down t"make newplants. Strong-growing varie- 

 ties ..f //. h,Tl, ,i.-,is may be treated in the same way if 

 standard plaiils are desired. 



//, Iioiii'iiKi.i, which cannot withstand much more 

 than 10° of frost, is in the North much grown as a pot- 

 plant, especially the more showy varieties with large 

 heads of sterile fls., and is extensively used for outdoor 

 decoration during the summer. Late in fall, when the 

 Ivs. have fallen after frost, the plants are moved to a 

 frost-proof cellar and kept rather dry until spring, when 

 they are repotted in new soil and the growth of last 

 year cut back to 1 or 2 pairs of buds. As a suitable soil 

 may be recommended a Tuixtiire of loam, leaf -mold and 

 sand, with ground bone, ilrie.i c<.w immure or some other 

 kind of manure added. UuriiiL' the summer a liberal 

 supply of water should be i;jv,ii, aN.. o.-casionally ap- 

 plications of liquid manure, until tin- lis. h.ave developed. 

 They may also be planted in the open ground during 

 the summer, lifted late in fall with a large ball of earth, 

 stored over winter in a coldframe or pit and planted out 



