mm. long; stamens usually 20 to 35; achenes 100 to 300 in a head 5-12 mm. 

 long and 3-5 mm. in diameter. 



28. Ranunculus ranunculinus (Nutt.) Rydb. 



Glabrous terrestrial perennial; roots about 1 mm. thick; stems erect, not root- 

 ing. 1-3 dm. long, freely branching above; petioles 5-13 cm. long, the stipular 

 leaf bases 1-2 cm. long; basal leaf blades compound, ternately divided into 3 

 primary leaflets and these again nearly always ternately divided into secondariy 

 leaflets that are ternately lobed, parted or divided, the ultimate divisions tending 

 to be lanceolate to narrowly elliptic or ovate and 2-3 or rarely 8 mm. wide and 

 more or less coriaceous; cauline leaves alternate, similar to the basal or reduced, 

 the upper sessile; pedicels 1-3 cm. long in flower, usually 2-6 cm. long in fruit, 

 glabrous; sepals yellow tinged with green, spreading, narrowly elliptic, 3-6 mm. 

 long, 1.2-2.2 mm. wide, glabrous, thin, promptly deciduous; petals 5 or rarely 

 none or 1, yellow, narrowly obovate, 5-7 mm. long, 1.5-2.5 mm. wide; nectary 

 scale glabrous, not overhanging the nectary, consisting of a mere transverse callus 

 ridge below the gland; anthers elliptic, achenes 5 to 15 in a capitate cluster, 

 oblong, 2.5-3.5 mm. long, the thin pericarp marked on each face by 3 to 5 or 

 6 striations or branched nerves, glabrous, the style persistent and flexible in fruit 

 and 1.5-2 mm. long; receptacle pyriform, 1 mm. long in flower, 1-1.5 mm. long 

 in fruit, scaly, not hairy. 



In wet soils along streams and in seepage areas, in N. M. (Colfax and San- 

 doval COS.), May-June; Wyo. and lit., s. to N.M. 



29. Ranunculus aquatilis L. Fig. 465. 



Glabrous or hispidulous perennial; stems submersed, rooting at the lowest 

 nodes, 2-6 or rarely to 20 dm. long, branching, with large air chambers present 

 in the cortex, the vascular system far in the interior, sometimes hispidulous; 

 leaves usually all cauline, alternate, somewhat shorter than the internodes or 

 exceeding them; petioles to 3 cm. long, including the stipular leaf bases which 

 in the submersed leaves are 2-5 mm. long (these sometimes bordering the entire 

 petiole but usually not so); leaf blades often all submersed and finely dissected 

 into filiform divisions, usually repeatedly trichotomous, the leaf as a whole not 

 globular, usually but not necessarily collapsing when withdrawn from the water, 

 2-4 cm. long, 3-5 cm. wide; the upper leaves (when floating) simple, reniform 

 in outline, 1.5-2.5 cm. broad, 3-lobed and again lobed or parted and lobed, 

 with broad stipular bases; pedicels stout, 1—2 cm. long in flower, 1.5-3 cm. long 

 and not reflexed in fruit, glabrous; sepals 5, light-green, spreading, ovate, 2-3 mm. 

 long or sometimes longer, 1-1.8 mm. wide, glabrous, deciduous before the 

 corolla; petals 5, white or the bases yellow, 4—8 or 14 mm. long, 1.5-2 mm. 

 wide; nectary scale glabrous, forming a shallow pocket or sometimes greatly 

 reduced; stamens 5 or 10 to 25; achenes usually 10 to 20 in a globose cluster, 

 obovoid, 1-1.5 or rarely 2-2.5 mm. long, roughly transversely-ridged, glabrous 

 from the beginning or the pistils hispid and the achenes giabrate or with some 

 hairs persisting on or near the dorsal sutures, the margins rather sharp, the style 

 deciduous, the achene beak about 0.1-0.3 mm. long; receptacle subglobose, 1 

 mm. long in flower, 1 mm. long in fruit, densely pubescent. 



Commonly attached and floating in ponds, streams, pools and springs, often 

 in swift-flowing water, in N. M. (Rather widespread) and Ariz. (Apache, 

 Coconino and Yavapai cos.), Apr.-Aug.; Nfld. and Lab. to Alas., s. to N.C., Ind., 

 N.M., Ariz, and Baja Calif. 



Our plants are usually referred to var. capillaceus (Thuill.) DC, with stems 

 1-2.5 mm. thick and stamens usually 10 or more. 



955 



