54 JOURNAL OF THE ARNOLD ARBORETUM [vol. iv. 



KEY TO THE SPECIES 



Leaves petiolate, obovate to spathulate, an inch or more long, venation promi- 

 nent; flowers an inch or more in diameter 10. R. kamtschatievm. 



Leaves sessile, lanceolate to oblanceolate, less than an inch long, venation not 

 prominent; flowers less than an inch in diameter 11. R. Redowskianum. 



Rhododendron kamtschaticum Pallas, FL Ross. i. 48, t. 33 (1784). — 

 Chamisso & Schlechtendal in Linnaea, i. 513 (1826). — Loudon, Arb. Brit. 

 ii. 1139, fig. 9, 40 (1838).— De Candolle Prodr. vn. 726 (1839).— Hooker, 

 FL Bor. Am. n. 43 (1839). — Maximowicz in Mem. Acad. Sci. St. Petersb. 

 ser. 7, xvi. no. 9, 47 (Rhod. As. Or.) (1870). — Franchet & Savatier, Enum. 

 PL Jap. i. 293 (1875).— Kegel in Gartenfl. xxxvi 593, t. 1200 (1887). 

 Hutchinson in Bot. Mag. cxxxiv. t. 8210 (1908).— Schneider, 111. Handb. 

 Laubholzk. n. 507, figs. 331 p-r, 333-e (1909).— Wocke in Gartenwelt, 

 XIII. 554, fig. (1909).— Matsumura, Ind. PL Jap. n. pt. 2, 462 (1912).— 

 Bean, Trees & Shrubs Brit. IsL n. 363 (1914).— Miyabe & Miyake, FL 

 Sachal. 310, no. 386 (1915).— Millais, Rhodod. 198 (1917). 



Rhodothamnus kamtchaticus Lindley in Lindley & Paxton, Flow. Gard. i. 



113, t. 22 (1850).— Lemaire in Jard. Fleur. i. t. 53 (1851). 

 Therorhodion camtschaticnm Small in North Am. FL xxix. pt. 1, 45 (191 1). 



A much-branched shrub, 15-30 cm. high, current season's shoots sparsely 

 glandularly pilose, shining brown. Leaves deciduous, often crowded, 

 short-petioled, membraneous, obovate to spathulate*, 2.5-4 cm. long, 

 1-2.5 cm. wide, rounded and mucronate at apex, narrowed at base into 

 the ringed petiole, glandular-ciliate, reticulate above, venation prominent 



- 



below, with few strigose hairs on principal veins. Flowers solitary 1 or 

 racemosely 2-3 rose-purple, bowl-shape 2.5-3.5 cm. across; pedicels erect, 

 1.5-3.5 cm. long, glandularly pilose; bracts foliaceous; calyx green, foil- 

 accous, persistent, deeply 5-lobed, lobes oblong-elliptic, 1-1.5 cm. long 

 0.4-0.6 cm. wide, obtuse, mucronate, glandular-ciliate; corolla deeply 

 5-lobed, lobes spreading from a short tube 3-6 mm. long, elliptic to 

 ovate-elliptic, 1.5-2.5 cm. long, 1-1.5 cm. wide, villose at base within; 

 stamens 10, unequal, filaments color of corolla, villose near base, anthers 

 blackish; pistil longer than stamens, ovary conic, clothed with gray villous 

 hairs, style curved, stigma slightly capitate. Fruit ovoid, 1-1.2 cm. long, 

 glabrescent, enclosed within persistent calyx; seeds wingless, minute, 

 obovoid, shining yellow-brown. 



1 It is frequently stated that the flowers of R. kamtschaticum Pall, and its relative 

 R. Redowskianum Maxim, are borne on " special leafy shoots" or are "terminal on 

 leafy shoots." The flowers certainly develop from a "terminal 99 and "special" bud, 

 as they do in the sections Leiorhodium and Lepipherum of the subgenus Eurhododendron 

 but I would regard the "leafy shoot" as a bracteate peduncle which may bear a soli- 

 tary flower or it may develop into a few-flowered raceme by the appearance of from 

 one to three additional pedicels from the axils of the foliaceous bracts. That is this 

 peduncle is the homologue of the rhachis in the racemose-umbellate flowered species, 

 the difference being that it is more elongated, the pedicel often adnate for some dis- 

 tance giving the false appearance of dichotomous branching and that the bracts and bracte- 



oles are foliaceous instead of membranous. This peduncle or rhachis does not develop 

 any buds after the ripening of the fruit and is deciduous. 



