Voi,. II.] 



PEA FAMILY. 



275 



i. Trifolium agrarium L. Yellow or Hop-clover. 



Trifolium agrarium ~L,. Sp. PI. 772. 1753. 



Glabrous or slightly pubescent, annual, ascend- 

 ing, branched, 6 / -i8 / high. Leaves petioled; stip- 

 ules linear-lanceolate, acuminate, 4 // -7 // long, ad- 

 nate to the petiole for about one-half its length; 

 leaflets all from the same point, sessile, obovate or 

 oblong, finely denticulate, narrowed at the base, 

 rounded, truncate or etnarginate at the apex, 6 // -9 // 

 long; peduncles axillary, > / -2 / long; head oblong, 

 or oval, 6 // ~9 // long, densely many-flowered; flowers 

 yellow, 2 // ~3 // long, at length reflexed; pedicels 

 shorter than the calyx; standard slightly emarginate, 

 exceeding the pod, conspicuously striate, and brown, 

 especially when dry. 



Along roadsides and in waste places, Nova Scotia to 

 Virginia, west to Ontario, western New York and Iowa. 

 Naturalized from Europe. May-Sept. 



(Fig. 2070.' 



\ 



2. Trifolium procumbens L. Low, or Smaller 

 Hop-clover or Hop-trefoil. (Fig. 207 1 . ) 



Trifolium procumbens L,. Sp. PI. 772. 1753. 



Similar to the preceding species, but lower, more spread- 

 ing and more pubescent. Leaflets obovate, cuneate at the 

 base, rounded, truncate or emarginate at the apex, finely 

 denticulate, 4 // -7 // long, the lateral ones nearly sessile, the 

 terminal distinctly stalked; stipules ovate, adnate to the 

 lower part of the petiole, about 2" long; peduncles 3"- 

 I2 /X long; heads 2o-4o-flowered, globose or short-oval, 

 4"-6 // in greatest diameter; flowers yellow, at length 

 reflexed, about 2" long; standard dilated, not folded, 

 exceeding the pod, striate and brown when dry. 



In fields and along roadsides, frequent or occasional 

 throughout our area and in the southern States. Naturalized 

 from Europe. May-Sept. 



3. Trifolium dubium Sibth. Least Hop- 

 clover or Hop-trefoil. (Fig. 2072.) 



Trifolium dubium Sibth. Fl. Oxon. 231. 1794. 

 Trifolium minus Smith, Engl. Bot. pi. 1256. 1799. 

 Trifolium procumbens var. minus Koch, Fl. Germ. & 

 Helv. Ed. 2, 195. 1843. 



Straggling or ascending, nearly glabrous, stems 2'- 

 20' long, branching. Leaflets obovate, truncate or 

 emarginate at the apex, or even obcordate, denticu- 

 late, cuneate at the base, the lateral ones nearly ses- 

 sile, the terminal stalked; stipules ovate or lanceo- 

 late, adnate to the lower part of the petiole ; peduncles 

 3 // -i2 // long; heads nearly globose, 2"-$" in diam- 

 eter, 3-20- flowered; flowers about \ l / 2 /f long, turn- 

 ing brown, at length reflexed; standard exceeding 

 and folded over the pod, scarcely striate. 



In fields and waste places, New England, New Jersey 

 and in the southern States. Also in British Columbia. 

 Naturalized from Europe. Summer. Said to be the true 

 Shamrock. Called also Yellow Suckling, Wild Trefoil. 



