24 RANUNCULACE.«. 



Etymology. BaKucrpov, an ancient name, of obscure derivation. 



Properties. The roots are scarcely acrid, and often yield a bitter and 

 yellow coloring matter. 



Geographical Distribution. This genus, of about 50 known species, 

 is widely distributed through the northern temperate zone ; a few are also 

 found, in a corresponding climate, on the Himalaya Mountains and the equa- 

 torial Andes. 



Division. The genus comprises a variety of forms, and greatly needs 

 revision. The North American species belong to three groups, viz. : — 



§ 1. Thalictrum proper. — Achenia sulcate-angled, ovoid or oblong, 

 chiefly sessile, the seed conformed to the cell. Stigma elongated. Se- 

 pals caducous, shorter than the stamens. — Roots fibrose. Stems most- 

 ly branching and fistulous, alternate-leaved. Involucre none. Flowers 

 small, mostly panicled, often dicecio-polygamous or strictly dioecious. 



§2. Syndesmon, Hoffmansegg. — Achenia and seed as in § 1. Stigma 

 depressed. Sepals 5 - 10, longer than the stamens, merely deciduous. 

 — Root grumous, or fasciculate-tuberous. Stem simple, leafless, except 

 an involucre at the summit, like that of Anemone ; consisting of 2 or 

 3 trifoliohite leaves with long-petiolulate leaflets, but destitute of com- 

 mon petioles, thus simulating a whorl of 6 or 9 long stalked simple leaves. 

 Flowers few and umbellate, or single, pretty large, showy, perfect. 



§3. Physocarpum, DC. — Achenia stipitate, inflated, veiny-striate or 

 even, the cell much larger than the seed. Sepals merely deciduous. — 

 Roots fibrose. Stems usually branching, alternate-leaved. Flowers 

 corymbose, scattered, perfect or polygamous. 



PLATE 6. Fig. 1-8. Thalictrum (Syndesmon) anemonoides, Michx. 



1. A stamen, magnified. 



2. A separate pistil, magnified. 



3. Transverse, and 4, vertical section of the same. 



5. Detached ovule, magnified. 



6. Head of ripe achenia, enlarged. 



7. Separate achenium, enlarged. 



8. Vertical section of the same, and of the seed, showing the embryo. 



9. Enlarged flower of T. (Physocarpum) clavatum, DC. (Gray, in Sill. 



Jour. 42. p. 17) ; — from the mountains of North Carolina. 



10. A magnified stamen, from the same. 



11. A pistil, magnified. 



12. Vertical section of the same, showing the ovule. 



13. Ovule, more magnified. 



14. Vertical section of an achenium, seed, and embryo. 



15. Embryo detached and much more magnified. 



