Puberulent or scabrous herbs, with thick opposite leaves, or the upper alternate, and small nodding, axillary and solitary, spicate racemose or paniculate heads of greenish flowers. Involucre hemispheric or cup-shaped, its bracts few, rounded. Receptacle chaffy, the linear or spatulate chaff enveloping the flowers. Marginal flowers 1-6, pistillate, fertile, their corollas short, tubular or none. Disk-flowers perfect, sterile, their corollas funnelform, 5-lobed, their styles undivided, dilated at the apex. Anthers entire at the base, yellow, scarcely coherent with each other, tipped with mucronate appendages. Achenes compressed, obovoid, glabrous. Pappus none. [Named after Ajuga Iva, from its similar smell.]

About 15 species, natives of America. Besides the following, 7 others occur in the southern and western United States. Type species: Iva annua L.

Heads spicate or racemose, each subtended by a linear or oblong leaf. Heads solitary, pedicelled.

Bracts of the involucre 4-5; heads 11/2"-2" high. Leaves serrate, oval or oblong; eastern.

1. I. frutescens.

Leaves entire or nearly so, obovate or oblong; western.

2. /. axillaris.

Bracts of the involucre 6-9; heads 3"-4" high; southeastern.

3. I. imbricata.

Heads spicate-paniculate; leaves dentate.

4. I. ciliata.

Heads spicate-paniculate, not subtended by leaves.

5. I. xanthiifolia.

1. Iva Frutescens L. Marsh Elder. High-Water Shrub

Fig. 4120

Iva frutescens L. Sp. Pl. 989. 1753.

Iva or aria Bartlett, Rhodora 8: 26. 1906.

Perennial, shrubby or herbaceous, somewhat fleshy; stem paniculately branched above, minutely pubescent, or sometimes glabrous below, 3°-12° high. Leaves oval, oblong, or oblong-lanceolate, all the lower ones opposite, short-petioled, 3-nerved, acute or obtusish, serrate, narrowed at the base, the lower 4'-6' long, 1'-2' wide, the upper smaller and narrower, passing gradually into those of the racemose inflorescence which are much longer than the short-pedicelled heads; involucre depressed-hemispheric, its bracts about 5, orbicular-obovate, separate; fertile flowers about 5, their corollas tubular.

Along salt marshes and on muddy sea-shores, Massachusetts to Florida and Texas, the northern plant (I. oraria) mainly broader-leaved and less shrubby than the southern. Jesuits'- or false Jesuits'-bark. July-Sept.

2. Iva Axillaris Pursh. Small-Flowered Marsh Elder

Fig. 4121

Iva axillaris Pursh, Fl. Am. Sept. 743. 1814.

Perennial by woody roots; stems herbaceous, ascending, glabrous or sparingly pubescent, simple or branched, 1°-2° high. Leaves sessile, entire or very nearly so, obtuse, faintly 3-nerved, obovate, oblong, or linear-oblong, 1/2'-1 1/2' long, thick, somewhat fleshy, glabrous or pubescent, the lower opposite, the upper alternate and smaller, passing gradually into those of the inflorescence; heads mostly solitary in the axils of the leaves, 2"-3" broad, short-peduncled; involucre hemispheric, about 1 1/2" high; its bracts about 5, connate at the base, or united nearly to the summit; pistillate flowers 4 or 5, their corollas tubular.

In saline or alkaline soil, Manitoba and North Dakota to western Nebraska, New Mexico, British Columbia and California. May-Sept.