ROSE FAMILY 411 



hypanthium glabrous ; sepals ovate-obtuse ; petals rose-colored, 1 . 5 mm. long, obovate ; follicles 

 oblanceolate, about 4 mm. long including the short beak, glabrous and shining. 



Rocky ridges, Boreal Zones; British Columbia to Oregon. Type locality: Blue Mountains, Oregon. June-Aug. 



Spiraea densiflora subsp. splendens (Baumann) Abrams. (.Spiraea betulifolia var. rosea A. Gray. Proc. 

 Amer Acad 8- 381. 1872. Spiraea splendens Baumann ex K. Koch, Monats. Ver. Bef. Gart. Preuss. 18: 294. 

 1875 " Spiraea arbuscula Greene, Erythea 3: 63. 1895.) Distinguished from the typical species by the finely 

 puberulent twigs, petioles, hypanthiums and veins on the under surface of the leaves. This subspecies is the 

 common form in the southern Cascades, Oregon, and in the Sierra Nevada, California. 



2. Spiraea lucida Dougl. Shiny Spiraea. Fig. 2366. 



Spiraea lucida Dougl. ex Hook. Fl. Bor. Amer. 1: 172, as a synonym. 1832; Greene, Pittonia 2: 221. 1892. 



Spiraea betulifolia Hook. Fl. Bor. Amer. 1: 172. 1832. Not Pall. 1784. 



Spiraea corymbosa var. lucida Zabel, Handb. Laubh. Deuts. Dendr. Ges. 157. 1903. 



A low shrub, with creeping rootstock, and erect glabrous stems and branches, 3-10 dm. 

 high. Leaves obovate or oval, 2-6 cm. long, glabrous, shining above, coarsely and irregularly 

 serrate; panicle flat-topped, 3-10 cm. broad; hypanthium glabrous; sepals about 1 mm. long; 

 petals white, orbicular, 2 mm. long; follicles glabrous and shining. 



Along mountain streams, Boreal Zones; British Columbia to Oregon, Wyoming, and Montana. Type 

 locality: valleys of the Rocky Mountains. June-Aug. 



3. Spiraea Menziesii Hook. Menzies' Spiraea. Fig. 2367. 



Spiraea Menziesii Hook. Fl. Bor. Amer. 1: 173. 1832. 



Spiraea cuneifolia Raf. New Fl. 3: 67. 1838. 



Spiraea Douglasii var. Menziesii Presl, Epimel. Bot. 195. 1852. 



A low shrub with erect branches, 8-20 dm. high. Leaves elliptical, 3-5 cm. long, short- 

 petioled, serrate above the middle, dark green above, pubescent, green and nearly or quite 

 glabrous beneath; panicle elongated, very narrow and dense; hypanthium sparingly villous- 

 pubescent; sepals soon reflexed, about 1 mm. long; petals rose-colored, suborbicular, 1.5 mm. 

 long ; follicles glabrous and shining, about 2 mm. long. 



Low ground and along streams, Humid Transition and Canadian Zones; Alaska to Oregon and Idaho. Type 

 locality: northwest coast of America. June-Aug. 



4. Spiraea Douglasii Hook. Douglas' Spiraea. Fig. 2368. 



Spiraea Douglasii Hook. Fl. Bor. Amer. 1 : 172. 1832. 



A shrub, 1-25 m. high with erect branches. Leaves short-petioled, elliptical to oval or 

 oblong-cuneate, 3-10 cm. long, usually acute at both ends, serrate above the middle, dark 

 green above, white-tomentose beneath; panicle narrow, elongated and congested; hypanthium 

 tomentose; sepals reflexed; petals rose-colored, about 1.5 mm. long; follicles about 3 mm. 

 long, glabrous and shining. 



Low ground and along streams, Humid Transition and Boreal Zones; British Columbia to northern Cali- 

 fornia. Type locality: northwest coast, about the Columbia. June-Sept. 



Spiraea subvillosa Rydb. N. Amer. Fl. 22: 251. 1908. Perhaps a hybrid between S. Douglasii and 

 S. densiflora. It differs from the other species having flat-topped panicles and pink flowers by the reflexed sepals. 

 The type is from the Oregon side of the Cascades of the Columbia; it also has been found near Hood River. 



Spiraea pyramidata Greene, Pittonia 2: 221. 1892. Perhaps a hybrid between S. lucida and S. Menziesii; 

 it is distinguished from the former by the reflexed sepals and from the latter by the white flowers and ovoid 

 instead of elongated panicle. Along streams and in wet places, Transition Zone; British Columbia to Idaho and 

 Oregon. Type locality: Yakima River, near Clealum, Washington. 



Spiraea tomentulosa Rydb. N. Amer. Fl. 22: 251. 1908. Leaves tomentose beneath; panicle short, 

 obovoid; sepals reflexed; petals white. Perhaps a hybrid between S. lucida and 5". Douglasn. Originally col- 

 lected in Falcon Valley, Washington. 



4. PETROPHYTUM Rydb. Mem. N.Y. Bot. Gard. 1:206. 1900. 



Cespitose woody plants with prostrate branches, growing on rocks. Leaves persistent, 

 crowded, oblanceolate or spatulate, entire. Flowers racemose, perfect. Sepals 5, valvate. 

 Petals 5, imbricate, white; stamens about 20. Pistils 3-5; ovary densely pubescent; style 

 filiform. Follicles dehiscent along both sutures. [Greek, meaning rock and plant.] 



About 4 or 5 species, natives of western North America. Type species : Spiraea caespitosa Nutt. 



Leaves 3-nerved. 



Sepals obtuse; leaves glabrate. L P- Hendersonii. 



Sepals acute; leaves canescent. 2. P. cinerascens. 



Leaves 1 -nerved ; canescent. 3 - P. caespitosum. 



1. Petrophytum Hendersonii (Canby) Rydb. Henderson's Rock-spiraea. 



Fig. 2369. 



Eriogynia Hendersonii Canby, Bot. Gaz. 16: 236. 1891. 

 Luetkea Hendersonii Greene, Pittonia 2: 219. 1892. 

 Spiraea Hendersonii Piper, Erythea 7: 172. 1899. 

 Petrophytum Hendersonii Rydb. N. Amer. Fl. 22: 253. 1908. 



Densely cespitose with short stout branches. Leaves spatulate, 1-2 cm. long, thick, more 



