Thalictrum macrostylum

Small & A. Heller

Mem. Torrey Bot. Club 3: 8. 1892.

Endemic
Synonyms: Thalictrum subrotundum B. Boivin
Treatment appears in FNA Volume 3.

Stems erect to ± reclining, slender, 50-200 cm, glabrous. Leaves basal and cauline; basal and proximal cauline petiolate, distal cauline sessile; petioles and rachises glabrous, neither pubescent nor glandular. Leaf-blade ternately and pinnately decompound; leaflets grayish green to brownish to bright green, nearly orbiculate to ovate or obovate, apically undivided or shallowly 2-3-lobed, 5-16 (-22) × 3-18 mm, length 1-3.3 times width, leathery and prominently reticulate abaxially, or sometimes quite membranous, margins sometimes revolute, lobe margins entire; surfaces abaxially glabrous. Inflorescences racemes or panicles, elongate, few flowered; peduncles and pedicels neither pubescent nor glandular. Flowers either unisexual with staminate and pistillate on different plants, or bisexual and unisexual with staminate and bisexual on some plants, pistillate and bisexual on others; sepals 4 (-6), greenish to white, nearly orbiculate, 1-2 mm; filaments white, filiform or sometimes clavate, 1.8-4 mm, rigid to flexible; anthers 0.5-1.2 mm. Achenes numerous, slightly stipitate; stipe 0.3-0.7 mm; body ovoid, 3-4.5 mm, prominently veined, glabrous; beak 0.7-1.7 mm. 2n = 56.


Phenology: Flowering late spring–summer (early Jun-mid Jul).
Habitat: Low woods, rich wooded slopes, cliffs, swampy forests, meadows, and limestone sinks
Elevation: 500-800 m

Distribution

V3 926-distribution-map.gif

Ala., Fla., Ga., Miss., N.C., S.C., Va.

Discussion

Much variation in Thalictrum macrostylum seems to be associated with habitat differences, especially the amount of sunlight received. The name T. subrotundum merely represents plants of T. macrostylum growing in deep shade. Common garden studies and cluster analyses do not support recognition of two species (M. Park 1992).

Selected References

None.

Lower Taxa

None.
... more about "Thalictrum macrostylum"
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.12 cm1.2 mm <br />0.0012 m <br />) +
Marilyn M. Park +  and Dennis Festerling Jr. +
Small & A. Heller +
cuneate +, truncate +  and cordate +
Leucocoma +  and Undefined sect. Leucocoma +
straight +
0.07 cm0.7 mm <br />7.0e-4 m <br /> (0.17 cm1.7 mm <br />0.0017 m <br />) +
0.3 cm3 mm <br />0.003 m <br /> (0.45 cm4.5 mm <br />0.0045 m <br />) +
globose;cylindric +
Ala. +, Fla. +, Ga. +, Miss. +, N.C. +, S.C. +  and Va. +
500-800 m +
clavate +  and filiform +
0.18 cm1.8 mm <br />0.0018 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
showy +  and inconspicuous +
bisexual +  and unisexual +
unisexual +
0 cm0 mm <br />0 m <br /> (41 cm410 mm <br />0.41 m <br />) +
stipitate +, sessile +  and aggregate +
falcate;ovoid;obovoid +
Low woods, rich wooded slopes, cliffs, swampy forests, meadows, and limestone sinks +
compound +  and simple +
whorled +, opposite +  and alternate +
cauline +  and basal +
1.6 cm16 mm <br />0.016 m <br /> (2.2 cm22 mm <br />0.022 m <br />) +
grayish green +  and brownish +
0.5 cm5 mm <br />0.005 m <br /> (1.6 cm16 mm <br />0.016 m <br />) +
nearly orbiculate +  and ovate or obovate apically undivided or shallowly 2-3-lobed +
membranous +  and leathery +
0.3 cm3 mm <br />0.003 m <br /> (1.8 cm18 mm <br />0.018 m <br />) +
palmate +  and pinnate +
crenate;entire +
distinct +
conspicuous +
reduced +
pubescent;glabrous +
Flowering late spring–summer (early Jun-mid Jul). +
1 +  and 16 +
Mem. Torrey Bot. Club +
elongate +
pubescent;glabrous +
not arillate +  and stalked +
greenish;white +
not persistent +
distinct +
orbiculate +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
ribbed +  and veined +
erect +  and more or less reclining +
slender +
50 cm500 mm <br />0.5 m <br /> (200 cm2,000 mm <br />2 m <br />) +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.07 cm0.7 mm <br />7.0e-4 m <br />) +
persistent +
Thalictrum subrotundum +
Thalictrum macrostylum +
Thalictrum sect. Leucocoma +
species +
herbaceous +  and woody +