318 POLYGON ACE^}. (BUCKWHEAT FAMILY.) 



4. R. maritimus, L. Simple or diffusely branched, the low stems erect 

 or procumbent, minutely pubescent : leaves linear lanceolate, usually truncate or 

 cordate at base, 1 to 4 inches long, mostly on short petioles, somewhat wavy- 

 margined : flowers in numerous dense verticils along the slender branches : valves 

 ovate-lanceolate, with 2 or 3 long-owned teeth on each side, all grain-bearing. 

 From the Sierra Nevada eastward across the continent. 



2. Flowers dioecious or polygamous in naked panicles : valves not grain-bearing: 

 leaves often hastate, sparingly veined : stems erect and slender, glabrous.* 



5. R. paucifolius, Nutt. Roots thickened : leaves narrowly to linear- 

 lanceolate, or the lowest broader, attenuate to a slender petiole, not very acid : 

 flowers reddish, in loose fascicles ; pedicels filiform, jointed at base : valves 

 enlarged in fruit, cordate-ovate, entire, twice longer than the akene. From 

 Utah and Montana to the Sierra Nevada and Washington Territory. 



6. POLYGONUM, L. KNOTWEED. 



Flowers perfect. Annual or perennial leafy herbs, rarely woody at base : 

 sheaths naked, ciliate, or foliaceous-margined : flowers small, in axillary, spi- 

 cate, or racemose fascicles. 



1. Flowers in axillary fascicles or spicate with foliaceous bracts : leaves and 

 bracts jointed upon a very short petiole adnate to the naked 2-lobed or lacerate 

 sheath : perianth 5 to 6-parted, more or less herbaceous, dose-appressed to the 

 akene: stamens 3 to 8, the three inner filaments broad at base: styles 3 : akene 

 triangular. AVICULARIA. 

 * Flowers in the axils of leaves or in loose virgate spikes : sepals herbaceous or 



colored only on the margin. 



- Branches leafy to the summit: sheaths short and mostly scarious, at length 



lacerate. 2 



1. P. erectum, L. Rather stout, erect or ascending, glabrous, usually tinged 

 with yellow : leaves oblong or oval : flowers often yellowish, on more or less ex- 

 serted pedicels : sepals and stamens 5, rarely 6 : akene very broadly ovate to 

 lanceolate, dull and granular to nearly smooth and shining. From Colorado to 

 Nevada and Oregon and the Eastern States. 



2. P. minimum, Watson. Very low and slender, ascending, rarely 6 inches 

 high, usually more or less scabrous-puberulent : stems nearly terete, reddish: 

 leaves ovate to oblong, sometimes all narrowly lanceolate : flowers in all the 

 axils, usually small, erect on slender exserted pedicels, often tinged with rose- 

 color: stamens 5 to 8 : akene smooth and shining. Bot. King Exped. 315. 

 P. Torreyi, Watson, Am. Nat. vii. 664. From the Wahsatch and Uintas to 

 California and Oregon. 



1 R. Acetosella, L., is the common "Sorrel" of fields and gardens, spread everywhere 

 from Europe. It can be distinguished from R. pauciflorus by its slender running roots, more 

 hastate and very acid leaves with the lobes often toothed at base, pedicels very short and 

 jointed at the top, and the valves not enlarged nor exceeding the small akene. 



* P. aviculare, L., may be known by its prostrate or spreading habit, sessile lanceolate or 

 oblong leaves, dull broadly ovate akene which is minutely granular under a lens. Intro- 

 duced from Europe and growing everywhere about yards and roadsides. Variously called 

 " Knot-grass," " Goose-grass," or " Door-weed." 



