ROSACEAE 
545 
(false Acacia, locust) is cultivated in S. Brit. Stipules thorny. The 
leaflets move upwards in hot or dry air. The horizontal shoots 
branch in one plane, while the upright show radial symmetry (p. 47). 
The base of the petiole forms a cap protecting a series of axillary buds. 
Rochea DC. Crassulaceae. 4 sp. S. Afr. [For R. falcata DC. see 
Crassula.] 
Rodgersia A. Gray. Saxifragaceae (1). 1 sp. China, Japan. 
Rodriguezia Ruiz et Pav. Orchidaceae (28). 25 sp., epiphytic, in 
trop. Am. Between successive tubers there is often a long stretch of 
rhizome. 
Roella Linn. Campanulaceae (1. 1). 11 sp. S. Afr. 
Roemeria Medic. Papaveraceae (11). 3 sp. Medit. to Afghanistan. 
R. hybrida DC. has become established as a cornfield weed in Norfolk 
and Cambridgeshire. 
Roettlera Vahl = Didymocarpus Wall. 
Rohdea Roth. Liliaceae (vn). 1 sp . R. japonic a Roth, Japan. “It 
is, according to Delpino, a link between the Asparagoideae and the 
Araceae. It possesses a kind of spadix, on which the firs, are 
arranged in a close uninterrupted spiral. The fact that the limb 
of the perianth is spread out exactly on a level with the points of the 
anthers and stigma led D. to think that fertilisation was effected by 
small animals crawling over the firs. He observed snails {Helix 
aspersa &c.) greedily eating the perianth, which is yellow and fleshy; 
after devouring about 10 firs, they crawled to another spadix. Only 
those firs, on which the snails had crawled proved fertile; the firs, 
were found to be barren to their own pollen. These observations 
leave no doubt that snails are really efficient fertilising agents.” 
(Muller.) 
Romulea Maratti. Iridaceae (1). 50 sp. Eur., Medit. (1 Brit., rare). 
Rondeletia Linn. Rubiaceae (1. 3). 60 sp. trop. Am. 
Roridula Linn. Droseraceae. 2 sp. S. Afr. Like Drosera, but with 
no movement of the leaf-tentacles. 
Rosa Tourn. ex Linn. Rosaceae (in. 10). 100 sp. N. temp, and on 
trop. mts. ; 6 in Brit., inch R. canina L., the dog-rose. A variable 
genus like Rubus (pp. 117, 119). The fir. of R. canina is a pollen 
fir. (p. 88). The fruit (hip) consists of a number of achenes enclosed 
in the fleshy receptacle which closes over them after fertilisation. 
R. centifolia L. is the form from which the cabbage rose is derived ; 
and numerous forms of this and other sp. are cultivated (see Nat . PJR)» 
The thorns of roses are mere epidermal appendages. 
Rosaceae. Dicotyledons (Archichl. Rosales). 90 gen. with 2000 sp. 
cosmop. Trees, shrubs and herbs, usually perennial; leaves alt. (exc. 
Rhodotypos), simple or compound, usually stip., the stipules often 
adnate to the petiole. Vegetative multiplication occurs in various 
ways, but especially by creeping stems — runners as in strawberry, 
or suckers as in raspberry. The firs, are terminal, in racemose or 
35 
w. 
