=A. pyrenaicum= (Pyrenean).* _fl._ yellow, rather large; spur hooked; bottom of helmet cylindrical, rounded; racemes elongated, dense, puberulous. June. _l._ parted almost to the base, with pinnatifid lobes, rather hispid beneath, but smooth above, on long stalks. _h._ 2ft. Pyrenees, &c., 1739.
=A. squarrosum= (rough). Synonymous with _A. barbatum_.
=A. vulparia= (Fox-bane).* _fl._ pale yellow, smooth; spur spiral; helmet cylindrical, large; beak stretched out, acute; racemes crowded. July. _l._ three or five-lobed, ciliated. _h._ 1ft. to 3ft. Europe, 1821. SYN. _A. lupicidum_. The principal varieties of this species are:--
=A. v. carpaticum= (Carpathian). _fl._ panicled, of a lurid colour, sometimes variegated with yellow; helmet conico-cylindrical, compressed; peduncles smooth. _l._ profoundly cut. Stems smooth. _h._ 2ft. to 3ft. Carpathian Mountains, 1810.
=A. v. Cynoctonum= (tall Dog's-bane). _fl._ (and stem) yellow, smoothish, numerous, panicled. _h._ 3ft. to 4ft. France, 1820.
=A. v. moldavicum= (Moldavian). _fl._ violet, panicled; helmet cylindrical, compressed. _h._ 3ft. to 4ft. Moldavia.
=A. v. rubicundum= (reddish). _fl._ livid violet, panicled, villous, variegated with yellow; helmet conico-cylindrical, compressed. _h._ 2ft. to 3ft. Siberia, 1819.
=A. v. septentrionale= (northern).* _fl._ blue, panicled, villous; helmet conico-cylindrical, compressed. _h._ 4ft. North Europe, 1800.
=ACORN.= The seed or fruit of the oak. _See_ =Quercus=.
=ACORUS= (from _a_, without, and _kore_, the pupil of the eye; in allusion to its reputed medicinal qualities). ORD. _Aroideæ_. A small genus of hardy herbaceous plants. Flowers on a sessile spadix; perianth six-cleft, inferior, persistent. They thrive best in a moist soil, and are very suitable for the banks of water, or even as aquatics in shallow water. Propagated easily by divisions during spring.
=A. Calamus= (sweet-flag).* _fl._ yellowish, small, borne on a cylindrical spadix 4in. to 6in. long. Summer. _l._ sword-shaped, erect, striated 3ft. long. The root is cylindrical, channelled, and very fragrant. Europe. The variety with gold-striped leaves is more useful as a decorative plant. See Fig. 20.
=A. gramineus= (grass-leaved). China, 1796. This is much smaller in all its parts than the above, but very pretty.