Flowers usually monœcious, in globular heads or catkins; the sterile arranged in a conical cluster, naked; stamens very numerous, intermixed with minute scales; filaments short. Fertile flowers consisting of many 2-celled 2-beaked ovaries, subtended by minute scales in place of a calyx, all more or less cohering together and hardening in fruit, forming a spherical catkin or head; the capsules opening between the 2 awl-shaped beaks. Styles 2, stigmatic down the inner side. Ovules many, but only one or two perfecting. Seeds with a wing-angled seed-coat.--Catkins racemed, nodding, in the bud enclosed by a 4-leaved deciduous involucre. (A mongrel name, from _liquidus_, fluid, and the Arabic _ambar_, amber; in allusion to the fragrant terebinthine juice which exudes from the tree.) 1. L. Styracíflua, L. (SWEET GUM. BILSTED.) Leaves rounded, deeply 5--7-lobed, smooth and shining, glandular-serrate, the lobes pointed.--Moist woods, from Conn. to S. Ill., and south to Fla. and Tex. April.--A large and beautiful tree, with fine-grained wood, the gray bark commonly with corky ridges on the branchlets. Leaves fragrant when bruised, turning deep crimson in autumn. The woody pods filled mostly with abortive seeds, resembling sawdust. ORDER 39. HALORÀGEÆ. (WATER-MILFOIL FAMILY.) _Aquatic or marsh plants (at least in northern countries), with the inconspicuous symmetrical_ (perfect or unisexual) _flowers sessile in the axils of leaves or bracts, calyx-tube coherent with the ovary_ (or calyx and corolla wanting in Callitriche), _which consists of 2--4 more or less united carpels_ (or in Hippuris of only one carpel), _the styles or sessile stigmas distinct_. Limb of the calyx obsolete or very short in fertile flowers. Petals small or none. Stamens 1--8. Fruit indehiscent, 1--4-celled, with a single anatropous seed suspended from the summit of each cell. Embryo in the axis of fleshy albumen; cotyledons minute. 1. Myriophyllum. Flowers monœcious or polygamous, the parts in fours, with or without petals. Stamens 4 or 8. Leaves often whorled, the immersed pinnately dissected. 2. Proserpinaca. Flowers perfect, the parts in threes. Petals none. Leaves alternate, the immersed pinnately dissected. 3. Hippuris. Flowers usually perfect. Petals none. Stamen, style, and cell of the ovary only one. Leaves entire, in whorls. 4. Callitriche. Flowers monœcious. Calyx and petals none. Stamen 1. Ovary 4-celled, with 2 filiform styles. Leaves entire, opposite. 1. MYRIOPHÝLLUM, Vaill. WATER-MILFOIL.