86 GENUS AHTEMISIA. 



the average for wrighli, but in other plants from near the type locality (Eulalia Plains, September 29, 1885, 

 Wilhinson, US 227800), the height and breadth are 4.0 and 3.8 mm., respectively. As is seen from table 6, 

 the total number of flowers is about the maximum for subspecies urighti, while the number of ray-flowers is 

 considerably higher than in any other collection examined. In the Eulalia Plains specimens, however, the 

 proportion between the number of flowers in ray and disk is about normal, but the total is astonishingly high, 

 there being 10 to 14 in the ray and 24 to 28 in the disk. This is so exceptional that the counts have not been 

 entered in the table. The type is from plains near the city of Chihuahua, Pringle 625 (Gr). 



65. A. PUDICA Rydberg, Bull. Torr. Club 32:130, 1905. — A. vulgaris gnaphalodes. A form with thinnish 

 leaves, loosely branched inflorescence, and nodding heads, such as to be expected in moist shady places. The 

 most striking character lies in the inflorescence, which is composed of many long, erect racemiform branches. 

 But this may be due in some cases to injury to the growing tip of the central axis, thus causing an exceptional 

 development of the branches. Such injury is plainly evident in some specimens on the type sheet, as also 

 among duplicates of the type, while other specimens of the same collection show no evident injury. Type 

 locality, Gunnison, Colorado. 



66. A. PUMILA Nuttall, Trans. Am. Phil. Soc. ii, 7:399, 1841.— Not A. pumila Link 1822. A reduced form 

 of A. vulgaris lindleyana only 1 to 1.5 dm. high. Type locality, in the Rocky Mountains, Lewis River, by 

 ponds or in depressions. 



67. A. PUESHIANA Besser, in Hooker, Fl. Bor. Am. 1:323, 1833. — A. vulgaris gnaphalodes. The leaves are 

 supposedly broader, but since the types of gnaphalodes are wanting all but the upper leaves, this can not be 

 verified and, indeed, is of no importance in view of the wide range of variation in leaf-width. According to 

 Rydberg (N. Am. Fl. 34:273, 1916), the flowers over the range assigned to purshiana are light-brown or yel- 

 lowish, while true gnaphalodes, which is assigned only to districts from the Rocky Mountains east, has dark- 

 brown or purplish coroUas. But even according to this discriminating authority, purshiana sometimes occurs 

 as far east as Nebraska. While it seems to be true that the corolla-color is usually lighter in plants from west 

 of the Rocky Mountains, there is much variation in the shade and the criterion is diflScult of application, 

 especially to dried specimens (see under Criteria, p. 39). The type locality of A. purshiana is plains of the 

 Saskatchewan. 



68. A. PURSHIANA ANGUSTIFOLIA Besser, 1. c. — Probably a very narrow-leaved form of A. vulgaris longifolia. 

 Type locality. Red River. 



69. A. PURSHIANA LATIFOLIA Besser, 1. c. — A. vulgaris gnaphalodes, from the description. (See A. purshiana 

 of this list.) 



70. A. REDOLENS Gray, Proc. Am. Acad. 21:393, 1886. — A. vulgaris redolens. 



71. A. REvoLUTA Rydberg N. Am. Fl. 34:272, 1916. — A. vulgaris mexicana. The leaves are divided into 

 very narrow lobes (2 to 4 mm. wide) and the margins of these are more noticeably revolute than in most speci- 

 mens. Apparently a response to strongly xerophytic conditions. Type locality, near the city of Chihuahua. 



72. A. RHizoMATA NclsoH, BuU. Torr. Club 27:34, 1900. — A variation of A. vulgaris gnaplialodes with inter- 

 rupted inflorescence, semiwoody rhizomes, and usually narrow leaves. Found on low saline flats adjacent to 

 streams. Type locality, Sweetwater River, Wyoming. 



73. A. RHIZOMATA PABULARis Nelson, 1. c, 1900. — A slender competition-form of A. vulgaris gnaphalodes, 

 the types from saline draws of the Red Desert of Wyoming, growing with grasses. Leaves only 2 to 5 mm. 

 wide. According to Rydberg (N. Am. Fl. 34:273, 1916), the corollas are light-brown as contrasted with 

 the dark-browTi corollas of gnaphalodes, but those on the type sheets appear dark-brown or nearly purplish. 



74. A. SELENGENsis Turczaiiinov; Besser, Nouv. Mem. Soc. Nat. Mosc. 3:50, 1834. — This Eurasian species 

 has been accredited to North America by Rydberg (N. Am. Fl. 34:266, 1916) on the basis of supposedly 

 introduced plants collected at Lower Albina, near Portland, Oregon (Sheldon 1115, NY, US). There is good 

 reason to believe, however, that these plants represent one of the many forms of A. vulgaris heterophylla, which 

 is common in Oregon. The lower leaves are wanting, so that there is no evidence of the double lobing of true 

 selengensis. The upper leaves can be almost duplicated in native west-American forms (see, for example, 

 the figures on p. 41). The heads are small for heterophylla, but they are immature and not smaller than on 

 many native plants at the same stage. When compared with European material of true selengensis, these Oregon 

 plants are seen to possess the same general appearance, and especially the remarkably smooth upper surface 

 of the leaves. But that species, or rather form, for it is often considered a minor variation of typical A. vulgaris, 

 has characteristics not found in these, especially the presence of 1 or 2 pairs of stipule-like lobes on the lower 

 part of the petiole. These structures are almost universally absent from heterophylla. The petiole in the 

 Oregon plants referred to selengensis is devoid of lobes, although there are a few reduced leaves in the axils 

 which may easily be mistaken for lobes. Even if selengensis can be demonstrated to be distinct from A. vulgaris 

 typica, its admission to the North American flora may await further evidence. 



75. A. SERRATA Nuttall, Genera 2: 142, 1818. — A. vulgaris serrala. 



76. A. siLVicoLA Osterhout, Bull. Torr. Club 28:645, 1901. — Best referred to A. vulgaris ludoviciana, but 

 the leaves mostly entire, very green above, and the heads rather large. Reduced to a variety of mexicana 

 by Nelson, but lacks the long and narrow leaf-lobes which furnish the only distinguishing feature of that sub- 

 species. Rather common in partial shade in Colorado. Type locality, Maclntyre Creek, Colorado. 



