388 NORTH AMERICAN FLORA [VoLumE 22 
posed to be a native of Canada. It appears to differ from S. officinalis in the more elongated 
spike and long-exserted filaments. No native plant of eastern North America agrees with 
the description. A species with purple flowers and long-exserted filaments occurs on the 
west coast and this was referred to S. media by Hooker. It has, however, much broader 
leaflets than those figured by Zanoni and by Morison. In Dictionnaire des Sciences Natu- 
relles p/. [240] there is a good illustration of a plant named S. media and agreeing in 
every respect with the description and the older illustrations. This is figured as having 
filiform filaments, not dilated as they are in S. Menziesti. S. media must either bean Old 
World species or else a garden hybrid or derivative of S: officinalis. 
35. POTERIDIUM Spach, Ann. Sci. Nat. III. 5: 43. 1846. 
Leafy branched annuals or biennials, with tap-roots. Leaves odd-pinnate, with adnate 
stipules and pectinately pinnatifid leaflets. Flowers greenish, perfect, in dense, oblong 
spikes. Hypanthium urn-shaped, contracted at the mouth, 4-winged. Sepals 4, green 
with white-scarious margins. Stamens 2 or 4, opposite all or the inner two sepals; filaments 
short. Pistils solitary; styles terminal ; stigmas brush-like; ovules solitary, suspended. 
Achenes enclosed in the 4-winged, indurate, dry hypanthium. 
Type species, Sanguisorba annua Nutt. 
Fruiting hypanthium with thin wings about 0.5 mm. wide, not reticulate on the faces; stamens 
usually 4; sepals tuberculose-thickened at the base. 1. P. annuum, 
Fruiting hypanthium with very narrow thick wings, more or less reticulate on 
the faces; stamens usually 2; sepals not conspicuously thickened at the base. 2. P. occidentale. 
1. Poteridium annuum (Nutt.) Spach, Ann. Sci. Nat. III. 5: 43. 1846. 
Poterium annuum Nutt.; Hook. Fl. Bor. Am. 1: 198. 1832. 
Sanguisorba annua Nutt.; T. & G. Fl. N. Am. 1: 429. 1840. 
_ Glabrous annual or perhaps rather biennial, with a tap-root ; stem branched, leafy, 1-4 
dm. high; leaves odd-pinnate; stipules of the basal leaves entire, those of the stem-leaves 
pectinately divided; leaflets 7-15, broadly obovate, 7-12 mm. long, pectinate-pinnatifid 
with obtuse, linear-oblong or linear, mostly spreading divisions; spikes at the ends of the 
branches, oblong-cylindric to globose, 0.5-3 cm. long, about 7 mm. thick ; bracts and bract- 
lets ovate, shorter than the flowers, scarious-hyaline; sepals broadly oval, apiculate, 2 mm. 
long, green with broad white-scarious margins ; stamens usually 4; filaments filiform, short ; 
fruiting hypanthium ovoid, 2.5 mm. long, with strong thin wings, which are nearly 0,5 
mm. wide, faces not reticulate. 
TVPE LOCALITY: Plains of Red River, Arkansas. 
DISTRIBUTION: From Arkansas to Kansas and Texas. 
ILLUSTRATION: Torrey, Marcy’s Rep. p/. 5. 
2. Poteridium occidentale (Nutt.) Rydberg. 
Poterium annuum Hook. Fl. Bor. Am. 1: 198, in part. 1832. 
Sanguisorba occidentalis Nutt.; T. & G. Fl. N. Am. 1: 429. 1840. 
Sangutsorba myriophylla A. Braun & Bouché, Ind. Sem. Hort. Berol. 1867: app. 10. 1868. 
Poterium myriophyllum Gay [misprint for Geyer] Select. Sem. Hort. Acad. Dresden. 1846.— 
A. Braun & Bouché, doc. cit. 
Glabrous biennial or perhaps perennial herb, with a tap-root; stem branched, leafy, 2~ 
10 dm. high; leaves glabrous, odd-pinnate ; stipules of the basal leaves entire, lanceolate; 
those of the stem-leaves foliaceous and pectinately cleft into linear segments; leaflets of the 
lower leaves 11-15, obovate, the larger 1-2 cm. long, pectinatély pinnatifid into 9-15 nar- 
rowly linear acute divisions, mostly strongly ascending; spikes at the ends of the branches, 
globose to oblong-cylindric, 0.5-2.5 em. or in fruit even 3-4 cm. long, 7-8 mm. thick; 
flowers hermaphrodite; bracts and bractlets ovate, concave, green on the midrib, with 
broad scarious-hyaline margins; sepals oval, white-margined, green in the middle, obtuse, 
apiculate, 2 mm. long; stamens 2, opposite the inner sepals; filaments filiform, short; 
fruiting hypanthium lance-ovoid, 4-angled with narrow, thick wings, reticulated on the faces. 
TYPE LOCALITY: Grand Rapids of the Oregon [Columbia River]. 
DISTRIBUTION: Southern British Columbia and western Montana to southern California. 
