1. Ceratophyllum demersum L. Common hornwort. Fig. 448. 



Plants entirely submersed; lowest leaves of seedling simple; stems prolonged, 

 sometimes to 3 m. long, branched and forming large masses, brittle or somewhat 

 cordlike and flexuous; leaves as many as 12 in a verticil, finely dissected into 

 capillary to linear and flattened serrate divisions, very variable as to the length, 

 breadth and toothing of the leaf divisions, usually about 15 mm. long; achene 

 compressed, ellipsoid, wingless, smooth. 4-6 mm. long, with 2 basal spines 2-5 

 mm. long; style 4-6 mm. long. 



In quiet waters of lakes, ponds and slow streams in most of Okla,. throughout 

 Tex. but mostly in the e. part of state, N. M. (Dona Ana, Grant and Rio Arriba 

 cos.) and Ariz, (widespread), summer; from Que. to n. B.C., s. to Mex.; also 

 Old World. 



The seeds and occasionally the foliage provide food for wildfowl especially 

 ducks. The usually dense growth, that may crowd out other more desirable species, 

 provides shelter for fish, shrimp and other small animals as well as a haven for 

 insects that are valuable as fish food. 



2. CeratophyUum echinatum Gray. 



Plants entirely submersed, closely resembling C. demersum; lowest leaves of 

 seedling cleft; stems prolonged and branched; leaves usually with entire capillary 

 divisions, 1.5-2 cm. long, the uncleft base somewhat expanded; achene narrowly 

 winged by the confluent bases of the lateral spines, with a somewhat tuberculate 

 surface, 5-7 mm. long; style 5-10 mm. long. C. demersum var. echinatum Gray. 



In quiet waters of streams, lakes and pools in n.e. Tex. (Bowie Co.), summer; 

 from Fla. to Tex. and Mex., n. to s.w. N.B., s. Me., N.Y., O., Mich., 111. and 

 Minn. 



Fam. 61. Ranunculaceae Juss. Crowfoot Family 



Herbaceous or occasionally woody plants; leaves basal, alternate or in a few 

 genera opposite or whorled; flowers hypogynous, regular or irregular (in 

 Delphinium), with all parts free and distinct or the pistils connate in Nigella; 

 sepals present, usually imbricate, varying from petaloid to small and caducous; 

 petals present or absent; stamens usually numerous; pistils 1 to many, simple; 

 ovules 1 to many; style 1; stigma lateral or terminal, usually minute; fruit an 

 achene, follicle or berry. 



Perhaps about 1,000 species in about 50 genera of world-wide distribution but 

 mostly in the forested parts of the North Temperate Zone. 



I. Carpels with 2 or more ovules; fruit follicular (2) 



1. Carpels with a solitary ovule; fruit an achene (6) 



2(1). Cauline leaves (at anthesis) in a dense cluster at the top of the woody 

 stem; wood yellow; flowers small, purplish-brown; staminodia 

 present; rare in southeastern Texas 1. Xanthorhiza 



2. Leaves, wood and flowers not as above; mostly from central Texas westward 



(3) 



3(2). Flowers irregular, large and showy, commonly blue or bluish (4) 



3. Flowers regular, mostly yellowish or whitish, rarely partly bluish (5) 



4(3). Upper sepal extended into a conspicuous cylindric spur 



4. Delphinium 



4. Upper sepal expanded into a helmet-shaped hood 5. Aconitum 



913 



