_Herbs, with small flowers in umbels (or rarely in heads), the calyx entirely adhering to the 2-celled and 2-ovuled ovary, the 5 petals and 5 stamens inserted on the disk that crowns the ovary and surrounds the base of the 2 styles. Fruit consisting of 2 seed-like dry carpels._ Limb of the calyx obsolete, or a mere 5-toothed border. Petals either imbricated in the bud or valvate with the point inflexed. The two carpels (called _mericarps_) cohering by their inner face (the _commissure_), when ripe separating from each other and usually suspended from the summit of a slender prolongation of the axis (_carpoph.o.r.e_); each carpel marked lengthwise with _5 primary ribs_, and often with 4 intermediate (_secondary_) ones; in the _interstices_ or _intervals_ between them are commonly lodged the oil-tubes (_vittae_), which are longitudinal ca.n.a.ls in the substance of the fruit, containing aromatic oil. (These are best seen in slices made across the fruit.) Seed suspended from the summit of the cell, anatropous, with a minute embryo in hard alb.u.men.--Stems usually hollow. Leaves alternate, mostly compound, the petioles expanded or sheathing at base, rarely with true stipules. Umbels usually compound, in which case the secondary ones are termed _umbellets_; the whorl of bracts which often subtends the general umbel is the _involucre_, and those of the umbellets the _involucels_.

The base of the styles is frequently thickened and cushion-like, and called the _stylopodium_. In many the flowers are _dichogamous_, i.e.

the styles are protruded from the bud some time before the anthers develop,--an arrangement for cross-fertilization.--A large family, some of the plants innocent and aromatic, others with very poisonous (acrid-narcotic) properties. The flowers are much alike in all, and the fruits, inflorescence, etc., likewise exhibit comparatively small diversity. The family is consequently difficult for the young student.

I. Fruit with the secondary ribs the most prominent, winged and armed with barbed or hooked p.r.i.c.kles, the primary ribs filiform and bristly.

1. Daucus. Calyx-teeth obsolete. Fruit flattened dorsally. Seed-face flat.

2. Caucalis. Calyx-teeth prominent. Fruit flattened laterally. Seed-face deeply sulcate.

II. Fruit with primary ribs only (hence but 3 dorsal ones on each carpel).

[*] Fruit strongly flattened dorsally, with the lateral ribs prominently winged.

[+] Caulescent branching plants, with white flowers.

[++] Lateral wings distinct; oil-tubes usually more than one in the intervals.

3. Angelica. Stylopodium mostly depressed, but the disk prominent and crenulate. Dorsal ribs strong. Stout perennials, with mostly coa.r.s.ely divided leaves.

4. Conioselinum. Stylopodium slightly conical. Dorsal ribs prominent.

Tall slender glabrous perennial; leaves thin, finely pinnately compound.

[++][++] Lateral wings closely contiguous; oil-tubes solitary; stylopodium thick-conical.

5. Tiedemannia. Dorsal ribs apparently 5, filiform. Smooth swamp herbs with leaves few or reduced to hollow cylindrical petioles.

6. Heracleum. Dorsal ribs filiform, the broad wings with a marginal nerve. Oil-tubes obclavate. Petals conspicuous. Tall stout perennials, with large leaves.

[+][+] Caulescent branching plants, with depressed stylopodium and yellow flowers.

7. Pastinaca. Fruit with filiform dorsal ribs, thin wings, and solitary oil-tubes.

8. Polytaenia. Fruit with a thick corky margin, obscure dorsal ribs, and very numerous oil-tubes.

[+][+][+] Acaulescent or nearly so, with filiform dorsal ribs, thin wings, and no stylopodium.

9. Peucedanum. Flowers white or yellow. Low western plants, of dry ground, with thick roots and finely dissected leaves.

[*][*] Fruit not flattened either way or but slightly, neither p.r.i.c.kly nor scaly.

[+] Ribs all conspicuously winged; stylopodium depressed or wanting.

10. Cymopterus. Low and glabrous, mostly cespitose perennials, with pinnately compound leaves and white flowers. Oil-tubes 1 to several.

Western.

11. Thaspium. Tall perennials, with ternately divided or simple leaves, and yellow flowers (rarely purple). Oil-tubes solitary.

[+][+] Ribs all prominent and equal but not winged; flowers white.

12. Ligustic.u.m. Ribs acute, with broad intervals. Stylopodium conical.

Oil-tubes numerous. Smooth perennials, with large compound leaves.

13. aethusa. Ribs very broad and corky, acute. Stylopodium depressed.

Oil-tubes solitary. Introduced annual.

14. Clopleurum. Ribs thick, corky (mostly obtuse). Oil-tubes solitary, adherent to the seed, which is loose in the pericarp. Stout glabrous sea-coast perennial.

[+][+][+] Dorsal ribs filiform, the lateral very thick and corky; oil-tubes solitary.

15. Crantzia. Small glabrous creeping perennials, rooting in the mud, with small simple umbels and leaves reduced to hollow cylindrical jointed petioles.

[*][*][*] Fruit flattened laterally.

[+] Carpels depressed dorsally; fruit short.

[++] Seed-face flat; flowers mostly yellow.

16. Fniculum. Ribs prominent. Oil-tubes solitary. Stout aromatic herb, with filiform-dissected leaves.

17. Pimpinella. Ribs filiform. Oil-tubes numerous. Glabrous perennials, with compound leaves.

[++][++] Seed-face concave; flowers white (yellow in n. 20); ribs filiform or obsolete.

18. Eulophus. Oil-tubes numerous. Stylopodium conical. Glabrous perennials from fascicled tubers, with pinnately compound leaves.

19. Anthriscus. Fruit linear, long-beaked, without ribs or oil-tubes, and with conical stylopodium. Leaves ternately decompound.

20. Bupleurum. Fruit oblong, with slender ribs, no oil-tubes, and prominent flat stylopodium. Leaves simple, perfoliate.

[+][+] Carpels terete or slightly flattened laterally; flowers white (except n. 24).

[++] Seed-face flat (or somewhat concave in n. 28); fruit short.

[=] Leaves 3-foliolate; stylopodium conical; oil-tubes solitary.

21. Cryptotaenia. Ribs obtuse, equal; fruit linear-oblong.

[=][=] Leaves once pinnate; stylopodium depressed; oil-tubes numerous.

Aquatic perennials.

22. Sium. Fruit ovate to oblong; ribs prominent, corky, nearly equal.

23. Berula. Fruit nearly globose; ribs inconspicuous; pericarp thick and corky.

[=][=][=] Leaves decompound. Oil-tubes solitary (none in n. 27).

Perennials.

24. Zizia. Ribs filiform; stylopodium none. Flowers yellow.