136 AMMIACEAE. 



carpellary or 1-carpellaiy. Ovaiy inferior. Fruit drupaceous or baccate, 

 or dry aud then a ci'emocarp, 



FA3IILY 1. AMMIACEAE. Carrot Fa^iily. 



Herbs with hollow stems. Leaves typically alternate : blades dis- 

 sected, or sometimes merely toothed, or entire. Flowers perfect or polyg- 

 amous, imibellate. Calyx of 5 tooth-like sepals, or obsolete. Corolla of 

 5 petals. Androecium of 5 stamens. Gynoecium of 2 united carpels, 

 often with a stylopodium. Fruit dry, a cremocarp, the ribbed or winged 

 carpels separating at maturity. 



Fruits with obscure or obsolete oil-tubes. 



Involucre wanting : fruits without secondary ribs or reticulations. 



1. Hydrocotylb. 

 Involucre conspicuous : fruits with secondary ribs and 



reticulations. 2. Centella. 



Fruits with distinct oil-tubes. 



Inflorescence glomerate, the flowers aggregated into dense 



heads. 3. Ekyngium. 



Inflorescence manifestly umbellate. 



Fruits flattened laterally, the carpels wingless. 4. Ptilimnium. 



Fruits flattened dorsally, the carpels winged. 5. Oxypolis. 



1. HYDROCOTYLB [Toiirn.] L. Perennial amphibious herbs. Leaves 

 solitary at each node. Umbels simple or proliferous. Sepals manifest. Petals 

 valvate. Carpels with distinct ribs, and oil-bearing tissues beneath the epi- 

 "lermis. — Marsh-pennywort. "Wateb-penxywort. 



Flowers, and fruits very short-pedicelled or sessile, in remote clusters along the 



rachis : fruits rounded or truncate at the base and the apex. 1. //. vcriicillaia. 



Flowers, and fruits slender-pedicelled : in terminal umbels: 



fruits notched at the base and the apex. 2. H. vmbcllata. 



1. H. verticillata Thunb. Leaf-blades suborbicular to oval, 1-6 cm. wide, 

 shallowlv creiiate: pedicels very short or wanting: fruits 3-4 mm. wide, with 

 slender ribs. — Everglades and shore-hammocks. — (Ber., Bah., Ant.) 



2. H. umbellata L. Leaf-blades suborbicular, 2-5 cm. wide, erenate or crenate- 

 lol'cd: pedicels slender, 4-12 mm. long: fruits about 3 mm. wide, with corky- 

 thickened ribs. — Everglades and low pinelands. — {Cuba, Ant.) 



2. CENTELLA L. Perennial amphibious jilants. Leaves clustered at 

 the nodes. Umbels capitate. Sepals obsolete. Petals imbricate. Carpels 

 without large oil-tubes, the prominent ribs anastomosing. 



1. C. repanda (Pers.) Small. Leaves clustered; petioles erect, 9-30 cm. long 

 (aVjout 2..5 cm. long, and with larger fruit, in C. repanda floridana) ; blades 

 thickish, ovate, 2-6 cm. long, repand, cordate or nearly truncate at the base: 

 peduncles usually several together, mostly shorter than the petioles: umbels 

 2-4-flowered: fruits 4-5 mm. wide. — Everglades. — {Ber., Bah., Cuba, Ant.) 



3. ERYNGIUM [Tourn.] L. Biennial or perennial herbs. Leaf-blades 

 spiny-toothed, lobed or incised or rarely entire. Bracts of the involucre often 

 colored, otherwise often resembling the leaves. Sepals acute or spine-like. 

 Petals 5, each prolonged into an infle.xed tip. Carpels with obsolete ribs and 

 5 oil-tubes. — Eryxgo. Button-snakeroot. 



Leaf-blades not parallel-veined. 



Basal leaves with entire or toothed blades. 1. E. liahUrinii. 



Basal leaves with pinnatlfld or pinnatoly parted blades. 2. E. arnninticum. 



Leaf-blades parallel-veined. 3. E. synchaetum. 



