CARROT FAMILY 439 
Borders of leaflets not notched . . . . .  Pimpinella 
Leaves of 3 to 7 radiating lobes. . . . . . ~~. # Sanicula 
Flowers Purple 
PPC VeRTAUNAPING ee ea os Mees, aMenla 
weaves ternately divided ~. «9. . 9. © «os Thaspium 
Flowers white. Seeds rounded or oval 
Leaves not compound 
1. ERYNGIUM, L. 
Herbs, with spiny toothed elongated leaves. In our two species the 
leaves are grass-like, with spines along both edges. Flowers are col- 
lected in dense heads, below each of which is an involucre of conspicuous 
bracts both at the base of the individual head and at the base of the 
group of heads. Calyx lobes somewhat leafy; petals white or bluish. 
1. E. aquaticum, L. (Fig. 6, pl. 109.) Burron SNAKE-RooT. Stem 
2 to 6 ft. high. Leaves from 1 to 2 ft. long, about an in. wide, with 
parallel veins and with the edges armed with spines. Heads rounded, 
averaging about 4 in. diameter. Low grounds, New Jersey and westward. 
July-Aug. 
2. E. virginianum, Lam. (Fig. 5, pl. 109.) Vircinta Erynoo. 
Stem 1 to 3 ft. high; leaves, the upper grass-like with spines at the 
borders; 2 to 8 in. long. The basal leaves long and narrow on a leaf- 
stalk. Heads about 4 in. diameter. Marshes near sea-coast, New Jersey 
and southward. July-Sept. 
By some authorities this is regarded as only a variety of H. aquaticum. 
z. HYDROCOTYLE, L. 
Marsh herbs, ours quite small, prostrate and rooting at joints. Leaves 
of our species round with leaf-stem near the middle; whole plant smooth. 
Flowers small, white in small heads, either simple or one head above 
the other on the flower stem. 
1. H. umbellata, L. (Fig. 4, pl. 111.) Marsa PEnnywort. Stem 
creeping, several in. long, rooting at joints. Leaf-stem arising from the 
creeping stem and above the small fasiculus of roots. Leaves round, veins 
radiating from near the center. Flowers in small round heads or umbels 
at the summit of the flower stem. Wet places, eastern Mass., and south- 
ward. Nearly all summer. 
2. H. Canbyi, C. and R. (Fig. 5, pl. 111.) Cansy’s PENNyworrt. 
Resembles No. 1, but flowers are in several small heads, one above the 
other on the flower stem. Flower stem considerably longer than leaves. 
Wet grounds, New Jersey and southward. June-Sept. 
3. H. verticillata, Thumb. (Fig. 6, pl. 111.) WHorrep Marsu 
PENNYworT. Flower heads very small, one above the other; the flower 
stem shorter than the leaves. Mass., and southward. June-Sept. 
4. H. americana, L. (Fig. 7, pl. 111.) AmertcAN MarsH PENNY- 
wort. Stems thread-like; leaf stem affixed near the border of the rounded 
