Heads many-flowered, usually radiate; rays pistillate. Involucre of one row of scales united into a firm cup, at the base some loose bractlets. Receptacle flat, not chaffy, but beset with short chaffy bristles. Achenes slender, 4-angled; pappus a row of chaffy scales dissected into numerous rough bristles.--Herbs, mostly annuals or biennials, dotted with large pellucid glands, which give a strong odor (as in Tagètes, the FRENCH MARIGOLD of the gardens, which belongs to the same group); heads terminating the branches; flowers yellow. (Name δυσωδία, _an ill smell_, which the plants exemplify.) 1. D. chrysanthemoìdes, Lag. Nearly smooth, diffusely branched (6--18´ high); leaves opposite, pinnately parted, the narrow lobes bristly-toothed or cut; rays few, scarcely exceeding the involucre.--Roadsides, and banks of rivers, Minn. to Ill., Tenn., and southwestward. Aug.--Oct. 66. ÁNTHEMIS, L. CHAMOMILE. Heads many-flowered, radiate; rays pistillate or (in n. 1) neutral. Involucre hemispherical, of many small imbricated dry and scarious scales shorter than the disk. Receptacle conical, with slender chaff at least near the summit. Achenes terete or ribbed, glabrous, truncate; pappus none or a minute crown.--Branching strong-scented herbs, with finely pinnately dissected leaves and solitary terminal heads; rays white; disk yellow. (Ἀνθεμίς, the ancient Greek name of the Chamomile.) A. CÓTULA, DC. (MAY-WEED.) Annual, acrid; rays mostly neutral; receptacle without chaff near the margin; pappus none; leaves finely 3-pinnately dissected. (Maruta Cotula, _DC._)--Common by roadsides. (Nat. from Eu.) A. ARVÉNSIS, L. (CORN CHAMOMILE.) Pubescent _annual or biennial_, resembling May-weed, but not ill-scented; leaves less finely 1--2-pinnately parted; chaff of the receptacle lanceolate, pointed; pappus a minute border.--Waste places; rare. (Adv. from Eu.) A. NÓBILIS, L. (GARDEN CHAMOMILE.) More downy and _perennial_, pleasantly strong-scented; sterile shoots depressed or creeping; leaves very finely dissected; chaff of the receptacle blunt; pappus none.--Established near Lewiston, Delaware, _Nuttall._ (Adv. from Eu.) 67. ACHILLÈA, L. YARROW. Heads many-flowered, radiate; the rays few, fertile. Involucral scales imbricated, with scarious margins. Receptacle chaffy, flattish. Achenes oblong, flattened, margined; pappus none.--Perennial herbs, with small corymbose heads. (So named because its virtues are said to have been discovered by _Achilles_.) 1. A. Millefòlium, L. (COMMON YARROW or MILFOIL.) Stems simple; _leaves twice-pinnately parted_; the divisions linear, 3--5-cleft, crowded; corymb compound, flat-topped; _involucre oblong; rays 4--5, short_, white (sometimes rose-color).--Fields and hills; common. Green and more glabrate in fields in the Atlantic States, and perhaps in such cases introduced. Aug. (Eu.)