1518 



RHODODENDRON 



and if gentle bottom heat can be given after callusing 

 it will be of advantage. They root, however, but slowly, 

 except those of the Javanese kinds, which are mostly 

 propatrated in this way, since they grow very readily 



Layering is sometimes practiced, especially with the 

 dwarf and small-leaved species, but the layers usually 

 cannot be separated until the second year. 



For the propagation of the numerous varieties and 

 hybrids of hardy and half-hardy Rhododendrons graft- 



2105. Azalea Sinensis, 



with Rhododendron. 



ing is most extensively employed. Rhododendron 

 Catawbiense or seedlings of any of its hardy hybrids 

 may be used as stock; li. maximum is also probably 

 as good. In English and Belgian nurseries E. Pouti- 

 cum, which is inferior in hardiness, is mostly employed 

 as a stock, but this often proves f.ifal if the grafted 

 plants are transferred to colder rlin ,t. - /,■ i rl.,,niim 



maybe used for strong-growiiiL' ■ '' Miid for 



cultivation in the greenhouse ■■: .h \ ^in . r ,,r 



side-grafting is mostly practi.-..i , i m - cLIt 



and saddle-grafting (see G.C. Ill I : ■ Ir.a.^ 



should be removed only partly :in., .i li.a.lnl 



back until the following year. li . m^ikiIIv 



done late in summer or early m i •<.■■ ^'inri- 



house on potted stock without u-iml' Lnainn - wax. ami 

 the grafted plants kept close and sliadcil until the union 

 has been completed. If large quantities are to be han- 

 dled the plants are sometimes not potted, but taken 

 with a suliicient ball of earth, packed close together and 

 covered with moss. Covering with moss to keep the 

 atmosphere moist is also of much advantage if the 

 plants are potted. See Figs. 2107, 2108. 



Distribution of Species. — About 200 species are 

 known, distributed through the colder and temperate 

 regions of the northern hemisphere; in tropical Asia 

 they occur in the mountains and extend as far south as 

 New Guinea and Australia, the greatest segregation 

 being in the Himalayas and E. Asia; several species 

 closely allied to those of tlie Malayan Archipelago are 

 found in the Philippine Islands, but are not yet intro- 

 duced ; 7 species occur in N. America. The species, with 

 few exceptions, are evergreen. 



Generic Description. — hys. lepidote. sometimes lepi- 

 dote and pilose, or quite glabrous or tomentose beneath : 

 fls. pedicelled, in terminal umbel-like racemes, rarely 

 lateral in 1- to f ew-fld. clusters ; calyx 5- parted, often very 



RHODODENDRON 



small; corolla rotatecampanulate to funnel-shaped or 

 sometimes tubular, with 5-10-lobed limb; stamens 5-20, 

 usually 10: ovary glabrous, glandular, tomentose or lepi- 

 dote, 5-10-Ioculed: capsule separating into 5 valves con- 

 taining numerous minute seeds. The Rhododendrons 

 possess but few eiamoniic pnipertifs. The hardy close- 

 grained wood of iIm iiiliMi, - 1 -|,, .ir~ i- u'-r.l for 



fuel; also for i ' i. ; the 



leaves of some ^i- ■ - > i, . i . - i .in, illy; 

 those of i^. ar^"/. "." :ii. I,.ii.viii \.. !.-■ |...i ..iip.us 'to 

 cattle. The flo\Mi» oi iaii,.a,, .-.j.rtu-.s an- .-..iiif times 

 made into a subacid jelly, bonie authors unite Azalea 

 with Rhododendron, but the two groups are very dis- 

 tinct horticulturally, however closely they may be allied 

 botanically. Azaleas are chiefly deciduous plants {A. 

 liiilirii 1111, stiy evergreen), usually with 5 exserted sta- 

 in. ns. I'l:;. L'lil.'i, Azalea Sinensis, also known as Bho- 

 ,l,ul, ,1,1 r,,H s,iii use, shovis the difference in looks be- 



ll,,ln 



- ^\: 



Is ha 



end. ni 

 as B. 



cultivated 

 was prob- 



Drigina'ted 



■ i~ In -I :\. -,.mI„.,1 and hgurcd 

 < ../»-./,- lAn.li. ws, Hot. Rep. 



(>-)79l. M : i I r -iiriilaioriij.in wen- .afterwards 



iais,.,l, I : : ,1 between true Rhododendrons 



»:i- IL i r \.:\^•,■eenB. Catawbiense aod 1{. 



('■■lih. nn.. I ,11 I - lint to have attracted much at- 



teiiti.iii. Ii \^,l- l> li, I'iidizing the product of this cross 

 with the Himalayan It. arboreum introduced about 1820 

 that the tirst plant was raised which became the fore- 

 runner of a countless number of beautiful hybrids. 

 Prom the appearance of this cross obtained about 1826, 

 at Highclere, in England, and therefore called B. Altu 

 clarense, the era of Rhododendron hybrids is to be dated. 

 Figs. 2104 and 2106 are common hybrid forms. A sec- 

 ond era in the history of the Rhododendron may be dated 

 from the introduotirm of a large nuuiber of the beau- 

 tiful Sikkiiii Hhnd.i.lrMdrons about 1850 and of the 

 Javanese -|h , i..^ -ImhiIv afterwards. A third era will 

 perhaps li'- ir,i. , ,l fr^ni the recent introduction of the 

 Yunnan Klinilci.liiMlrnns. Alfred Rehdeu. 



Hardy Rhodouendrons. — Rhododendrons, in this ar- 

 ticle, mean the evergreen sorts, more particularly B. 

 maximum and the hybrid varieties of JJ. Catawbiense; 

 in the main, however, the directions for the various oper- 

 ations apply to the Azalea group and to many other 

 members of the heath family. 



Propagation. — Rhododendrons are increased by seeds, 

 layers and grafts, and occasionally by cuttings. Seeds 

 slinuld be sown under glass, between January 1 and 

 M.iirh 15, in soil one-half peat, one-half pure fine sand, 

 with L'liud drainage. The seeds are small and require 

 11.1 i-.ivering, the usual watering after sowing being quite 

 sullieient. A thin layer of sphagnum over the surface of 

 the seed-pan is good protection from the sun and keeps 

 the soil evenly moist; it should be removed when ger- 

 mination begins. Seeds may also be sown on growing 

 sphagnum, a thin layer being compactly spread above 

 the seed soil and drainage, and an even surface being 

 secured by clipping. Seed-pans or flats of convenient 

 size are used and they should be plunged in sphagnum 

 still further to insure even moisture; the temperature 

 of the house should be 45°-.''.n° F. Smllings are prone 

 to damp-off and should be ]iri.-l<..l ..If int.. fresli soil as 



soon as they are big enough t.. Iiaii.ll.-; « Icii piiii-ers. 



made from a barrel hoop, ar.' liaii.U f..r tlii,s wi.rk. They 

 are slow growers and mu.st he ten. led carefully. Keep 

 under glass, well shaded until the weather is settled. 

 Frames with lath screens make good summer quarters. 

 Winter in pits and plant out in frames in peaty soil when 

 large enough. Never let them suffer from dryness. It 

 has been suggested that the seed of J?, maximum might 

 be planted on living moss under high-branched trees in 

 swamps where the water does not collect in winter. See 

 Jackson Dawson, on the "Propagation of Trees and 

 Shrubs from Seeds," Trans. Mass. Hort. Soc, 1885, part 

 1, p. 145. 



