DiPSACUs. LXXIV. DIPSACE^. 309 



1. F. Fagopyrum. Torr. & Gray. fValerianella radiata. Mmnch.) Wild 

 Corn-salad or Lamb Letlicce. — <SY. dicnotomous, nearly smooth ; Ivs. oblong- 



spatulate, subenlire ; fr. 3-sided, obscurely 2 — 3-toothed at the summit. — West- 

 ern N. Y. to Ohio ! Stem 8 — 18' in height. Bracts lanceolate, acute. Fruit 

 resembling that of buck-wheat (Polygonum Fagopyrum) in form, containing 

 one large seed and two empty cells. Flowers white. June. 



2. F. RADIATA. Michx. 



Lvs. entire, or toothed towards the base, obtuse ; Jls. white ; fr. ovoid, pu- 

 bescent, somewhat 4-angled, obscurely 1-toothed at apex ; empty cells not di- 

 vergent, but with a groove between them ; fertile cell flattish, broader than the 

 other 2.— Low grounds, Mich. ! Ohio ! to La. Stem 6—12' high, dichotomous 

 like the other species, smooth. Leaves oblong, more or less tapering to the 

 base, 1—2' by 2 — 4". Fruit less than 1" long, at length nearly smooth. May. 



3. F. OLiTORiA. Vahl. Pawnee Lettuce. 



Fr. compound, oblique, at length broader than long, not toothed at apex ; 

 fertile cell larger than both the others ; empty cells united, but with a groove 

 between ; lvs. spatulate-obtuse, radical ones petiolate ; Jls. pale blue. — Natural- 

 ized in some portions of the U. S. Stem smooth, 8 — 12' high, dichotomous. 

 Leaves mostly entire. Flowers in dense cymules. Fruit 1' diam. June. :j: 



4. F. uMBiLicATA. W. S. Sullivant. 



Fruit subglobose, inflated, apex 1-toothed, the anterior face deeply umbili- 

 cate, sterile cells several times larger than the fertile one; bracts subspatulate- 

 linear, not ciliate. — Columbus, Ohio, Sullivant ! Plant smooth in all its parts, 

 1 — 2f high, many times dichotomous. Leaves oblong, obtuse, clasping, dilated 

 and coarsely dentate at base, 1 J'— 3' by 3 — 10". Flowers in numerous cymules, 

 corymbosely arranged. Fruit nearly 1" diam., with 1 rib at the back produced 

 into a tooth at apex, and a coa.spicuous depression in front. 



Order LXXIV. DIPSACE^.— Teaselworts. 



lleris or !oio shrubs, with whorled or opposite leaves. , , ■ i 



Fls. collected upon a common receptacle and surrounded by a many-leaved mvolur.re. 



Cai adherent, often pappus-like, surrounded by a scarious involucel. 



Cor. tubular, somewhat irreaular, the limb 4— 5-parted. ,- • . 



Sm 1, alternate with the lobes of the corolla, often unequal. Anthers distmct. 



Ova inferior, one-celled, one-ovuled. S^y/c one, simple. 



Fr. dry, indehiscent, with a single suspended seed. 



Genera 6 species 150. The order is nearly allied to the Compositaa. The species are all natives of 

 the temperate resions of the Eastern continent, none of them American. Their properUes are unimpor- 

 tant. One of thespecies below is useful in dressing cloth. 



1. DIPSAcUS. 



■Gr. Siipao), to thirst; alluding to the water held in the axils of the leaves. 



Flowers in heads ; involucre many-leaved ; involucel 4-sided ; calyx 

 superior; corolla tubular, 4-cleft ; fruit 1 -seeded, crowned with the 

 calyx. — @ Plants large, hairy or prickly. Lvs. opposite, connate {some- 

 times distinct) at base. 



1. D. sYLVESTRis. Mill. Wild Teasel. 



Z/155. connate, sinuate or jagged; /t&. cylindrical ; bracts of the involucre 

 longer than the head of flowers, slender and pungent, bent inwards.— A tall, 

 naturalized, European plant, growing in hedges and by road-sides, Mass. to la. ! 

 Stem about 4f high, angled and prickly, with the opposite, lance-shaped leaves 

 united around it. Flowers bluish, in a large oval or cylindrical head whose 

 bracts or scales are not hooked as in the next species, but straight. July. % 



2. D. FuLLONUM. Fullers' TcaseZ.— Lrs. connate entire or serrate; M. cylin- 

 drical ; bracts hooked ; invol. spreading.— A cultivated, European plant. Root 

 fleshy, tapering. Stem erect, furrowed, prickly, hollow, about 5f high. Leaves 

 two at each node, united at their bases around the stem in such a way as to 

 hold a quantity of water. Flowers whitish, in large, oval or ovoid heads. Cul- 



