AMMIACEAE 861 



cm. long, cuneate-obovate to narrowly oblong, acute, serrate or incised, the teeth weakly 

 mucronate : involucre of minute bracts : rays mostly 2, only 2-10 mm. long : staminate 

 flowers very few or wanting : calyx and hypanthium 1 mm. long : sepals linear, acute : petals 

 minute, shorter than the sepals : fruits three together, short-stalked, subglobose, the peri- 

 carp thickish, with slender bristles : seeds 3-grooved on the back, with 5 oil-tubes. 



In woodlands, Vermont to Nebraska, south to Florida and Texas. Spring to fall. 



6. Sanicula Floridana Bicknell. Similar to S. Canadensis, but smaller and stiffer, 

 the stems more closely leafy. Leaves much smaller ; blades thicker, the divisions abruptly 

 cuneate with concave sides, acutely dentate-serrate and cut-lobed. with yellowish spiny- 

 cuspidate teeth : branches of the inflorescence slender, dichotomous, the branchlets stiff and 

 wide-spreading : involucre of very small or minute bracts : fruits very small. 



In sandy soil, South Carolina to Florida and Mississippi. Spring to fall. 



5. ERYNGIUM L. 



Biennial or perennial often rigid herbs, with erect or creeping stems. Leaves alter- 

 nate or whorled, sometimes mainly basal : blades spiny-toothed, lobed or incised, or rarely 

 entire. Flowers in dense capitate or elongated spikes. Bracts of the involucre various, 

 often colored, resembling the leaves. Sepals rigid, acute or spine-like. Petals 5, prolonged 

 into an inflexed acumination. Fruit varying from ovoid to obovoid, slightly laterally flat- 

 tened : carpels with obsolete ribs and 5 oil-tubes. Seeds slightly flattened. ERYNGO 

 BUTTON SNAKE-ROOT. 



Leaf-blades not parallel-veined. 



Blades of the basal leaves entire or merely toothed, sometimes spinulose, not spiny-toothed. 

 Stems filiform or relatively slender, like the branches mostly prostrate : plants biennial. 



Bractlets longer than the flowers : stem-leaves with narrow blades or segments : fruit strongly 



tuberculate.. 1. E. Baldwinii. 



Bractlets shorter than the flowers : stem-leaves with broad blades or seg- 

 ments : fruit not strongly tuberculate. 2. E. prostratum. 

 Stems relatively stout, erect or ascending : plants perennial or perhaps 



rarely biennial. 

 Lower leaves with elongated hollow petioles and long blades. 



Bractlets entire. 3. E. Floridanum. 



Bractlets 3- pronged. 



Teeth of the bractlets unequal, the lateral teeth smaller. 4. E. Virginianum. 



Teeth of the bractlets about equal. 



Heads fully 1.5 cm. long : plant mostly over 11 dm. tall. 5. E. Mettaueri. 



Heads about 1 cm. long : plant mostly less than 10 dm. tall. 6. E. Ravenelii. 



Lower leaves with short petioles and blades. 



Bractlets 3-toothed : upper leaves with merely toothed blades. 



Leaf-blades ovate, oblong or lanceolate, serrate or crenate : heads 



mostly over 7 mm. high. 7. E. integrifoUum. 



Leaf-blades linear or linear-lanceolate, laciniately toothed, at least 



near the base : heads mostly less than 7 mm. high. 8. E. Ludovicianum. 



Bractlets entire : upper leaves with palmately 5-7-parted blades. 9. E. Hookeri, 



Blades of the basal leaves lobed or parted, the segments spine-tipped, some- 

 times reduced to nodose phyllodes. 

 Heads 12 cm. long or less : sepals entire. 



Bracts of the involucre cleft or toothed : heads depressed or ovoid. 



Bracts of the involucre 3-cleft : bractlets 3-toothed. 10. E. aromaticum. 



Bracts of the involucre spiny-toothed : bractlets entire. 



Heads subglobose or depressed : bracts green within. 11. E. diffusum. 



Heads longer than broad : bracts conspicuously colored. 12. E. Wrightii. 



Bracts of the involucre entire : heads oblong or cylindric. 13. E. compactum. 



Heads 25-40 mm. long : sepals 3-5-toothed. 14. E. Leavenworthii. 



Leaf-blades parallel-veined. 



Bristles of the leaf-margins 2-4 together. 15. E. synchaetum. 



Bristles of the leaf-margins solitary. 16. E. aquaticum. 



1. Eryngium Baldwinii Spreng. Biennial, glabrous. Stems often branched at the 

 base, the branches very slender or filiform, 1-6 dm. long, prostrate or creeping : leaf-blades 

 various, those of basal leaves oblong, varying to broadest above or below the middle, 2-6 

 cm. long, entire or incised, long-petioled, those of stem-leaves smaller, 3-parted, the seg- 

 ments filiform, linear or oblong, entire or toothed : heads ovoid to cylindric, 4-6 mm. long : 

 bracts of the involucres subulate, shorter than the heads : bractlets similar but smaller : 

 fruit 1 mm. long or shorter, prominently tuberculate. 



In sandy soil, Georgia to Florida and Louisiana. Also reported from Missouri. Spring to fall. 



2. Eryngium prostratum Nutt. Biennial, glabrous or nearly so. Stems usually 

 branched at the base, the branches prostrate, often creeping, 2-5 dm. long, sometimes nearly 

 filiform : leaf-blades various, those of the basal and lower stem-leaves oblong or ovate, 2-4 

 cm. long, entire or repand, long-petioled, those of upper stem-leaves smaller, often clustered 

 at the nodes, some entire, others often 3-cleft : heads oblong, 5-6 mm. long : bracts of the 



