Thalictrum pubescens
Thalictrum cooleyi
King-of-the-meadow, late meadow-rue, meadow-weed, muskrat-weed, pigamon pubescent, tall meadow-rue
Cooley's meadow-rue
erect, coarse, 50-300 cm.
erect to reclining, slender, 60-200 cm.
blade ternately and pinnately decompound;
leaflets light to dark green, cordate or nearly orbiculate to ovate or obovate, apically undivided to 2-3(-5)-lobed or -toothed, 11-68 × 5-70 mm, length 0.8-2.6 times width, membranous to firm, margins scarcely revolute, lobe margins entire, surfaces abaxially pubescent to glabrous.
blade: proximal cauline mostly 2x-ternately compound, distal cauline usually ternately compound;
leaflets linear to narrowly lanceolate or oblanceolate, apically occasionally 2-3-lobed, 12-68 × 1-12 mm, length (2.6-)4-26 times width, membranous to leathery, margins sometimes revolute, lobe margins entire;
surfaces abaxially glabrous.
racemes or panicles to corymbs, apically ± rounded, many flowered;
peduncles and pedicels often pubescent.
racemes to panicles, elongate, few flowered;
peduncles and pedicels neither pubescent nor glandular.
unisexual or bisexual (sometimes bisexual with very few stamens);
sepals 4(-6), white to purplish, elliptic-rounded, 2-3.5 mm;
filaments ascending, white to purplish, filiform to distinctly clavate, 1.5-7 mm, usually rigid;
anthers 0.5-1.5(-2.1) mm, usually blunt or only slightly apiculate.
usually unisexual, staminate and pistillate on different plants;
sepals 4-5, white to yellowish in staminate flowers, greenish in pistillate flowers, obovate, 1.5 mm;
filaments white to purple, 2.5-6 mm;
anthers 0.9-2.5 mm.
numerous, sessile to stipitate;
stipe 0.5-1.5(-2.4) mm;
body ellipsoid, 3-5 mm, prominently veined, usually pubescent;
beak usually persistent, straight or coiled distally, 0.6-2.5 mm, about 1/2 length of achene body.
5-6, sessile or nearly sessile;
stipe 0-0.4 mm;
body ellipsoid, 4.5-6 mm, prominently veined, glabrous;
beak 1.3-2.4 mm.
= 126.
= 210.
Thalictrum pubescens
Thalictrum cooleyi
The ovaries change from white to purplish, becoming light green, then darker green, and finally brown as fruits mature.
Because of the polymorphic nature of Thalictrum pubescens, a proliferation of names for minor morphologic variants has resulted. Field studies (M. Park 1992) have shown that too much morphologic variation occurs within populations to support the recognition of previously described taxa. Plants in New England and northeastern Canada often have a corymbose inflorescence and longer filaments and achene beaks.
This species is often incorrectly treated in floras as T. polygamum Sprengel, an invalid name.
The Iroquois used Thalictrum pubescens medicinally a a wash for head and neck, to stop nosebleeds, and to treat gall (D. E. Moerman 1986).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Thalictrum cooleyi occurs commonly on Grifton soil and is associated with some sort of disturbance, including clearings, edges of frequently burned savannahs, roadsides, and powerline rights-of-way that are maintained by fire or mowing. Silvicultural and agricultural practices and their associated suppression of fire have seriously affected populations of T. cooleyi. Furthermore, fruit production appears to be quite low in the species (S. W. Leonard 1987).
Leaves of Thalictrum cooleyi have fewer leaflets than other species of Thalictrum sect. Leucocoma.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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