ERICACEAE. — RHODODENDRON 539 



subtus pallidiora, leviter olevato-reticulata, costa media supra imprcssa subtu3 

 elevata, nervis utrinsecus 10-12 supra leviter impressis v. fere obsoletis subtus 

 leviter elevatis; petioli crassi, 1-1.2 cm. longi, juniores puberuli. Flores 10-12 v. 

 plures, racemoso-umbellati; rhachis circiter 1 cm. longa, rufo-tomentosa; pedicelli 

 graciles, 1-1.6 cm. longi, tomento villoso cinereo-albido dense vestiti; bracteae 

 oblongo-obovatae v. oblanceolatae, utrinque villosae; calyx minutus, cupularia, 

 lobis 5, late triangularibus acutis 1-1.5 mm. longis sparse pubescentibus; 

 corolla campanulata, 2.5-3 cm. longa ac lata, 5-loba, lobis rotundatis circiter 

 1 cm. longis; stamina circiter 10, corollam subaequantia, filamentis 2-2.5 cm. 

 longis dilatatis supra medium villosis, antheris pallide roseis; ovarium conicum, 

 4-5 mm. longum, sparse albido-villosum; stylus curvatus, glaber, stigmata capi- 

 tato. Capsula desideratur. 



Shensi: Tai-pei-shan, 1910, W. Purdom (No. 4). 



This species is closely related to R. brachycarpum G. Don, a Japanese species, 

 which has rather differently shaped leaves white or dun-colored on the under 

 side, a more elongated inflorescence, longer pedicels and larger flowers. It is also 

 related to R. Przewalskii Maximowicz which has broader leaves, usually subcor- 

 date at the base and covered with rufous or pale tomentum beneath, glabrous 

 pedicels and an umbellate inflorescence. 



This species is named for William Purdom, in charge of the Arnold Arboretum 

 explorations in northern China during the years 1909, 1910 and 1911. 



Rhododendron gymnanthum Diels in Not. Bot. Gard. Edinburgh, V. 211 (PI, 

 Chin. Forrest.) (1912). 



Yunnan: Tse-kou, valley of upper Mekong river, T. Monbeig (No. 4). 



Our specimens differ from Diels' description in the longer calyx-lobes, in the 

 ovary being 7-9 mm. long, and in the partly short-acuminate leaves. We consider 

 this species as closely related to R. irrorattim Franchet and possibly some 

 specimens collected in Yunnan by A. Henry (Nos. 10275, 10853, 11066, 11067, 

 11067'*) and referred by Hemsley & Wilson {Kew Bull. Misc. Inform. 1910, 

 112) to R. irroratum, might be considered as constituting a pubescent variety of 

 R. gymnanthum. In his original description of that species {Bidl. Soc. Bot. France, 

 XXXIV. 280) Franchet describes the under surface of the leaves as glaucous and 

 the ovary as densely clothed with brown glands. In all Henry's specimens the 

 leaves are pale green below and the ovary is not glandular but densely covered 

 with rufous-gray tomentum. In No. 10853 the ovary is very sparsely tomentose. 

 The figure in the Botanical Magazine (LXX. t. 7361) of R. irroratum agrees with 

 Franchet's description except that the leaves are pale green below. Possibly the 

 species is very variable. P^re Monbeig's specimen is glabrous everywhere save 

 the rhachis of the inflorescence, which is very sparingly puberulous and totally 

 without glands. This and the racemose-umbellate inflorescence readily dis- 

 tinguish it from the R. irroratum Franchet, and from the specimens of Henry's 

 cited above. 



According to the description this new species is also near R. lukiangense Fran- 

 chet which has persistent bracts, shorter pedicels, smaller, differently shaped 

 flowers and inconspicuous calyx-teeth. 



Group f. 



Corolla 7-9-lobed (5-lobed in the preceding groups of this subgenus). Leaves 

 glabrous, cordate to abruptly contracted at the base (cuneate in a variety of 

 R. Fortund). 



