Herbs aquatic, with verticillate, dichotomously dissected leaves. Flowers mo.

ncecious, sessile, axillary, minute, with neither corolla nor calyx. Involucre 8 to 12cleft. Anthers (12 to 24) sessile. . A simple, 1-celled ovary. Seed suspended,

orthotropous, embryo with 2 pairs of cotyledons.

Genus 1 only, with 6? species, in the streams and pools of the northern hemisphere. Properties - Unimportant.

CERATOPHYL'LUM, L. Hornwort. (Gr. a horn, a leaf; alluding to the horn-like divisions of the leaves.) Character the same as that of the Order.

C. demersum L. Lvs. 6 to 8 in a whorl, doubly dichotomous, dentate-spines-cant on the back; fls. axillary; fr. 3-spined. - An aquatic weed in ditches, etc., N. Y. to Va., W. to I11. St. floating or prostrate, 8 to 16' long, filiform, with numerous whorls of leaves. These are dichotomously divided into 2 or more narrow, stiff segments. Fls. minute, axillary, sessile, with sessile anthers. Fr. an oblong, beaked capsule, with 1 seed. Jl. - Sept.

FIG. 692. Taxus Canadensis - naked seeds.

Class II. GYMNOSPERMae,

Exogenous plants with chiefly parallel-veined leaves, always diclinous, with the flowers very incomplete. Pistils none, or represented by open scales. Ovules axillary or naked, fertilized by the direct application of the pollen, becoming at maturity naked seeds, destitute of a true pericarp. Cotyledons often more than 2. This Class constitutes the

Cohort 4. CONOIDEae