6i— ROSA IWARA Siebold 
(ROSA RUGOSA x MULTIFLORA) 
Rosa Iwara : caulibus erectis, arcuatis, modice longis ; ramis viridibus, dense 
pubescentibus, aculeis copiosis, gracilibus, aciculis inaequalibus, setis glandulosis 
armatis ; foliolis 7, magnis, oblongis, acutis, viridibus, simpliciter serratis, haud 
rugosis nec valde venatis, utrinque glabris ; rhachi dense pubescente, haud glandu- 
losa ; stipulis angustis, adnatis, laciniatis, apice libero, angusto, laciniato ; pedicellis 
leviter hispidis ; calycis tubo parvo, globoso, nudo vel leviter aciculato ; lobis lanceo- 
latis, integris, longe productis, dorso dense pubescentibus ; petalis parvis, albis ; 
stylis liberis, hispidis, haud protrusis ; fructu parvo, rubro, globoso. 
R. Iwara Siebold ex Regel, Ind. Sern. Hort. Petrop. p. 53 (1861). — Regel 
in Act. Hort. Petrop. vol. v. p. 381 ( Tent . Ros. Monogr. p. 97 [1877]) (1878). — 
K. Koch, Dendrol. vol. i. p. 237 (1869). — Crepin in Bull. Soc. Bot. Belg. vol. xiii. 
p. 261 ( Primit . Monogr. Ros. fasc. iii. p. 268) (1874). — Rehder in Bailey, Cycl. Am. 
Hort. vol. iv. p. 1549 (1902). 
Stems erect, arching, moderately tall ; branches green, densely pubescent, with 
copious slender prickles, irregular aciculi and a few glandular bristles. Leaflets 7, 
large, oblong, acute, dull green, simply broadly serrated, not rugose or strongly 
veined, pubescent on both surfaces ; petioles densely pubescent, not glandular ; 
stipules narrow, adnate, laciniated, with narrow, laciniated free tips ; bracts large, 
pubescent, oblong or lanceolate; pedicels slightly hispid. Calyx-tube small, globose, 
naked or slightly aciculate ; lobes lanceolate, entire, long-pointed, densely pubescent 
on the back. Petals small, usually white. Styles free, hairy, not protruded beyond 
the disc. Fruit small, red, globose. 
Rosa Iwara is first mentioned in the Year-book of the Royal 
Horticultural Society of the Netherlands 1 for 1844. This volume 
contains a list of names of “old and newly imported Japanese and 
Chinese plants cultivated under the auspices of the Society in the 
nursery-garden of Siebold & Co. at Leyden, and on sale there.” In 
this list the plant is given as Rosa Iwara Siebold, habitat Japan, a 
decorative and medicinal shrub, imported by Siebold in 1832, raised 
from seed, and growing in the open air. 2 It is described as “ A 
species of Rosa multiflora which, notwithstanding its small, single, 
white flowers, may be regarded as one of the most beautiful of shrubs.” 
1 gaavboek van de Koninklijke Nederlandsche Maatschappij tot Aanmoediging van den Tninbonw (1845). 
2 P- 36. 
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