22 MASS. EXPERIMENT STATION BULLETIN 382 



Hamamelis. Witch-hazels have not been easily propagated by cuttings {.72), 

 80). Cuttings of H. mollis which were taken here in July rooted 59 percent 

 in sandy soil, less well in sand, without treatment; and those which were 

 treated with indolebutyric acid (50 mg./l., 20 hr.) rooted 72> percent in 

 sandy soil, less well in sand. 



Hedera Helix, English ivy, with the possible exceptioin of the variety con- 

 glomerata (5), is easily propagated by softwood cuttings, made of growing 

 tips (69, 83), inserted in sandy soil (80) or sand. Benefits of treatment 

 are not great (83) but rooting is sometimes hastened (113). Optimum 

 concentrations of indolebutyric acid are 10 mg./l., 24 hr., or 2 mg./gm. 

 talc (61). 



Helianthcmutn, sun-rose, is easily propagated by summer and early fall cut- 

 tings. Taken here in early October, cuttings of H. nummidariutu rooted 100 

 percent in sandy soil whether or not they were treated. 



Hclwingia japonica is not difficult to propagate by fall cuttings. Untreated 

 cuttings rooted 90 percent in sand when taken here in early November, 

 less well if taken in July. 



Hibiscus syriacus, shrubby althaea. Softwood cuttings which were taken 

 in July, a good month for this species (14), rooted 100 percent in 36 days 

 after treatment with indolebutyric acid (50 mg./l., 6 hr.), 52 percent 

 without it (83). Such cuttings are successfully made of side shoots, with 

 a heel, and rooted in sand (105). Rooting of hardwood cuttings, which 

 should be made of the basal or middle parts of the shoot rather than its 

 tip, was improved by treatment (48). Such cuttings, taken from October 

 to February, responded to treatment with indolebutyric acid 40 to 60 

 mg./l., 24 hr., 4 to 10 mg./cc. by the concentrated solution-dip method, 

 or 2 to 12 mg./gm. talc (49). 



Hydrangea. With the exception of H. petiolaris (18, 7Z, 113) and possibly 

 H. quercifolia, the species are easy to propagate by softwood cuttings taken 

 in summer, although those of H. arborescens (121) and H. petiolaris may root 

 more readily if taken in spring (102). At least for H. paniculata (16), H. 

 quercifolia, and H. macrophylla (87), sand-peat is a good rooting medium. 

 Rooting of cuttings of H. paniculata was hastened by indolebutyric acid (20 

 mg./l., 24 hr. (87). July cuttings of H. quercifolia rooted 100 percent in 

 sand in 39 days after treatment with Hormodin No. 2, 10 percent without 

 it (102). Their rooting was also improved or hastened by treatment with 

 indolebutyric acid, 1:250, in talc (104) or 30 mg./l., 10 hr. (83). 



Hypericum. St. John's-worts are not difficult to propagate by summer 

 cuttings made of tips of branches (105) and rooted in sandy soil (7). 

 Cuttings of H. frondostim, treated or not, rooted 100 percent in sand in 7 

 weeks when taken here in early August, less well if taken in June. 



Idesia polycarpa. Cuttings taken here in late July rooted 76 percent in sandy 

 soil after treatment with indolebutyric acid (25 mg./l., 16 hr.), 40 per- 

 cent without it. 



Ilex cornuta. Summer cuttings root well if taken after young leaves have 

 become dark green (110). Cuttings have also rooted well when taken 

 as late as January (44). Rooting was hastened by treatment with a 

 40-unit solution of Hormodin A, 100 percent of the treated cuttings 

 rooting in 35 days (117), or with indolebutj^ric acid 30 to 80 mg./l., 

 24 hr. (125). 



Ilex crenata. Cuttings, torn from the plant at the base of the current 

 year's growth (61), root readily if taken in fall and winter (15, 107), even 



