784 



HYDRANGEA 



again in spring; this will not injure in any way the pro- 

 fusion of fls. In certain kinds of soil the pink Horten- 

 sias show a tendency to turn blue, and perhaps this 

 can be caused by adding iron filings or alum to the 

 soil. H. hortensis is also a valuable plant for forcing, 

 and is much grown for Easter, especially the var. Otaksa, 

 on account of its dwarfer habit. Handsome pot-plants 

 can be grown in one year from cuttings. In February 

 or March cuttings are inserted 

 in the propagating house with 

 slight bottom heat,and planted 

 in small pots as soon as they 

 are footed. During the sum- 

 mer they may be easily grown 

 in pots and plunged outdoors 

 in coal ashes or in any kind of 

 porous soil, transplanted sev- 

 eral times and freely watered 

 and occasionally manured ; or 

 they may be planted out in 

 rich soil, exposed to the full 

 sun, where water should be 

 liberally given and now and 

 then an application of liquid 

 manure. Last of September 

 they should be repotted in 8- 

 inch pots, kept shady some 

 days until established, and 

 afterwards exposed to the sun. 

 After the first frosts they may 

 be brought into a cool green- 

 house. If intended to have 

 them in flower for Easter, 

 they should be transferred 

 not later than the fore part 

 of January into a warmer 

 house, with a temperature 

 gradually rising from 50 to 

 60; the plants should be 

 freely watered, and about once 

 a week an application of 

 liquid manure given until the 

 flower buds are developed. The fls. should be almost 

 fully developed some time before they are desired, 

 that they may be hardened off in a cooler house, since 

 overforced plants are likely to collapse if exposed to 

 sudden changes of temperature. After flowering, the 

 plants are pruned and repotted or planted out and 

 treated as above described for cuttings, or they may be 

 thro.vn away and another set of plants raised from cut- 

 tings. 



H. petiolaris is a handsome climbing plant for cover- 

 ing walls and trunks of trees, and grows well in the 

 shade, but fls. freely only in the full sun. 



The Hydrangeas are readily prop, by cuttings of half- 

 ripened or nearly ripe wood under glass in summer 

 (Fig. 1111); also by hardwood cuttings, layers, suckers 

 or division of older plants. H. quercifolia is best propa- 

 gated by suckers or by layers of growing wood put down 

 in summer. Rarely increased by seeds, which are very 

 small, and should be sown in fall in pans or boxes and 

 only slightly covered with soil. 



About 25 species in N. and S. America, Himal. and E. 

 Asia. Lvs. without stipules : fls. perfect in terminal 

 panicles or corymbs, often with sterile marginal fls.; 

 calyx lobes and petals 4-5; stamens usually 10; styles 

 2-5, short: capsule 2-5-celled, dehiscent at "the base of 

 the styles, with many minute seeds. 



1111. Summer cutting of 

 Hydrangea paniculata. 



HYDRANGEA 



A. Erect or spreading shrubs : stamens 10: petals 



panding. 

 B. Inflorescence pyramidal . 



1. paniculata, Sieb. Shrub or small tree, to 30 ft., 

 with dense globose head: Ivs. elliptic or ovate, acumi- 

 nate, serrate, sparingly pubescent above, more densely 

 on the veins beneath, 2-5 in.: panicle 6-12 in. long: fls. 

 whitish, the sterile ones changing later to purplish ; 

 styles 3: capsule with the calyx about at the middle. 

 Aug., Sept. Japan. S.Z. 61. The following varieties are 

 cult. : Var. floribunda, Regel. Panicles large, with more 

 and larger sterile fls. Gt. 16:530. Var. grandifldra, 

 Sieb. (var. hortensis, Maxim.). Fig. 1112. Almost all 

 fls. sterile ; panicles very large and showy. P.S 

 16:1665-66. Gn. 10:37 and 54, p. 376. R.H. 1873:50. 

 Mn. 8:119. A. G. 18:313. Gng. 3:357 and 5:3. F.E. 8:214. 

 S.H. 1:174. Var. praecox, Rehd. Almost like the type, 

 but flowering about 6 weeks earlier, in the middle of 

 July. G.F. 10:363. The late flowering typical form is 

 sometimes called var. tardiva, Hort. H. paniculata, 

 var. grandiflora is the common Hydrangea of lawns. It 

 is seen to best effect when planted close in front of heavy 

 shrubbery. Cut back rather heavily in early spring. 



2. quercifdlia, Bartr. Shrub, w'th spreading branches 

 to 6 ft.- young branches densely ferrugineously tomen- 

 tose: Ivs. long-petioled, roundish or broadly ovate, pin- 

 nately lobed with serrate lobes, glabrous above at length, 

 whitish tomentose beneath, 4-8 in. long: panicle 47 in. 

 long: fls. pinkish white, the sterile ones turning pur- 

 ple. June. Ky. to Alab. and Fla. B.M. 975. Gng. 2:305. 

 Hardy at Philadelphia. 



BB. Inflorescence corymbose, flat or globular. 

 o. Cyme without involucre at the base. 



D. Styles usually 2: capsule with the calyx at the 

 apex. 



3. arborescens, Linn. (H. urticifblla, Hort.). Erect 

 shrub, 4-10 ft. : Ivs. long-petioled, ovate, acute or acu- 

 minate, rounded or cordate at the base, serrate, green 

 and glabrous on both sides or somewhat pubescent or 

 glaucous beneath, 3-6 in. long : cymes 2-5 in. broad, 

 with none or few sterile fls. June, July. N. J. to Iowa, 

 south to Fla. and Mo. B.M. 13:437. Var. cordata, Torr. 

 & Gr., has the Ivs. broadly ovate and cordate. Var. 

 sterilis, Torr. & Gr. Almost all fls. sterile, known also 

 as Hills of Snow. 



4. radiata, Walt. (H. nivea, Michx.). Similar to the 

 former, but Ivs. densely whitish tomentose beneath and 

 cymes always with sterile fls. June, July. N. C. to Mo., 

 south to Ga. B.B. 2:185. Var. canescens, Dipp. (H. 

 canescens, Hort. H. cinerea, Small). Lvs. grayish to- 

 mentose beneath, sometimes pubescent above. Tenn. to 

 Ga. -Hardy about Philadelphia. 



DD. Styles usually 3 : capsule ivith the calyx near the 

 middle. 



5. vestita, Wall. (H. heteromdlla, Don. H. pubfs- 

 cenSf Decne.). Shrub, to 10 ft.: petiole deeply grooved 

 and margined, red: Ivs. ovate, acuminate, densely se- 

 tosely dentate, almost glabrous above, densely whitish- 

 tomentose beneath, 4-8 in. long : cyme 5-8 in. broad, 

 with bracts ; sepals of sterile fls. elliptic or obovate, 

 acute or mucronulate : capsule with the calyx above the 

 middle. June, July. Himal. F.S. 4:378-79. G.C. II. 

 22:617. 



6. Bretschneideri, Dipp. (H. vestita, var. yubescens, 

 Maxim. H. Pekinensis, Hort.). Shrub, to 8 ft. : petioles 

 not margined ; Ivs. ovate or elliptic-ovate to oblong- 

 ovate, acute or acuminate, serrate with short callous 

 teeth, more or less pubescent beneath, 3-5 in. long; 

 cymes similar to the former but smaller and denser, se- 

 pals roundish, obtuse: capsule with the calyx near the 

 middle. July. N. China, Setshuen. G.F. 3:17 and 6:396. 

 Var. glabrescens, Rehd. (H. serrata, Koehne, not 

 DC.). Lvs. smaller, elliptic, more coarsely serrate and 

 only sparingly pubescent. 



7. hortensis, Smith (H. HorUnsia, DC. H. opuloMes, 

 C. Koch. H. Japdnica, Sieb.). Shrub, to 8 ft., almos 

 glabrous : Ivs. ovate or ovate-elliptic, acuminate or 

 acute, coarsely serrate, 5-8 in. long: fls. in large cymes 

 without bracts, white, bluish or pink, few or all of 





