DiPSACus. LXXIV. DIPSACEiE. 309 



1. F. Fagopyrum. Torr. & Gray. rValerianella radiata, Manch.) Wild 

 Corn-salad or Land) Lettuce. — St. dicnotomous, nearly smooth ; Ivs. oblong- 



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

 ern N. Y. to Ohio ! Stems — 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 ; fis. white ; fr. ovoid, pu- 

 bescent, somewhat 4-angled, obscurely 1-toothed at apex ; eviply 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 \" long, at length nearly smooth. May. 



3. F. OLiTORiA. Vahl. Paionee 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 ; fls. pale blue. — Natural- 

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

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



4. F. UMBiLiCATA. W. S. Sullivaut. 



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^' — 3' by 3 — 10". Flowers in numerous cymules, 

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

 into a tooth at apex, and a conspicuous depression in front. 



Order LXXIV. DIPSACE^.— Teaselworts. 



Herbs or loio shruhs, with whorled or opposite leaves. 



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



Cal. adherent, often papiJus-like, surrounded by a scarious involucel. 



Cor. tubular, somewhat irregular, the limb 4— 5parted. 



Sta. 4, alternate with the lobes of the corolla, often unequal. Anthers distinct. 



Ova. inferior, one-celled, one ovuled. Style ona, simple. 



Fr. dr>', indehiscent, with a single suspended seed. 



Genera 6, species 150. The order i-^ nearly allied to the CompositaR. The species are all natives of 

 the temperate retrions of the Eastern continent, none of them American. Their properties are unimpor- 

 tant. One of the species below is useful in dressing cloth. 



1. DIPSACUS. 



Gr. iixpau), 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. — (1) Flanls large., hairy or prickly. Lvs. opposite^ connate (some- 

 times distinct) at base. 



\. D. sYLVESTRis. Mill. Wild Teasel. 



Z,t"s. connate, sinuate or jagged; Ar/5. 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 4rhigh, angled and prickly, with the ojiposite, 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. FcllOnum. Fullers' Teasel. — Lr5. connate entire or serrate ; M cylin- 

 drical ; ^rac/5 hooked ; z?/rr)/. 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 

 huld a quantity of water. Flowers whitish, in large, oval or ovoid lieatls. Cul- 



