Thalictrum cooleyi Sp. Nov.

Abstract

Planta 38-73 cm alta. Folia inferiora semper fere 2-ternata, raro 1-ternata aut 3-ternata. Foliola inferne glauca, margine revoluto, valde angusta, raro lobata. Planttae dioicae. Inflorescentita paniculata. Pedicelli 2-20 mm longi. Flores masculi flavi pallidi. Filamenta clavata, purpurea pallida, 2-3 mm longa. Antherae oblongo-lanceolatae, obtusae, flavae. Carpella matura 4.5-6 mm longa et 1.5-2.5 mm lata, ellipsoidea, glabra, sessilia vel subsessilia, 8-10 nervis conspicuis. This new species of Thalictrum was collected in the late spring and early summer of 1957 during extensive field work for "The Flora of the Carolinas," a project undertaken by a number of members of the Botany Department of the University of North Carolina. It is named in honor of George R. Cooley, a retired New York businessman, who is much interested in the flora of the southeastern United States. He has been and is actively supporting much research in this field. Thalictrtum cooleyi belongs to the section Leucocoma (Greene) Boivin. To this section belong T. dasycarpum, T. revoluturm, T. p,olygawmumn, T. macrostylum, and T. s'ubrotundum. It differs from all of these in having lavender instead of white filaments, narrowly lanceolate instead of oblong to ovate leaflets, and fewer leaf-divisions. Thalictrum cooleyi is a very slender-stemmed, glabrous plant averaging 47 cm in height with an infloreseence averaging 7 cm in length. The very lax stems are usually supported by surrounding vegetation. The caudex is short with a fibrous root system. The 3-5 basal leaves are mostly 2-ternate, rarely 3or 1-ternate. The three or foPr, rarely five, cauline leaves decrease rapidly upward both in size and in number of divisions, and are separated from one another by long internodes. The upper leaves, usually 1-ternate, are frequently sessile, occasionally subsessile or on short petioles up to 1 cm long. The leaflets, glaucous beneath, have revolute margins and are quite different from those of most other Thalictra in being very strikingly narrow and only occasionally lobed, particularly on the cauline leaves. The terminal leaflet of each division averages 15 mm in length and 7 mm in width on basal leaves, 20.5 mm in length and 4 mm in width on cauline leaves. Of the 58 terminal leaflets from which the above measurements were made, 15 were 3-lobed, 4 were 2-lobed and the remaining 39 were unlobed. The lateral leaflets of each division average 12 mm in length and 6 mm in width on basal leaves, and 16 mm in length and 4 mm in width on the cauline leaves. Of the 111 lateral leaflets measured, 10 were 3-lobed, 11 were 2-lobed and 90 were unlobed. The flowers are borne in an open panicle on pedicels up to 2 cm long. The sepals of staminate flowers, pale yellowish to white in color, are about 1.5 mm long and are very early deciduous. The filaments, slightly clavate, are pale lavender, 2-3 mm long. The lance-oblong anthers are obtuse, 1.5 mm long, and bright yellow. The pistillate flowers are greenish, with smaller sepals and pubescent stigmas, 1.5-2 mm long, as long as or longer than the glabrous ovary. The achenes