elongated, clavate, stipitate, 2-celled,-the upper cell larger. Lindl. GRASS PUCCINIA. Vulgo-Mildew. Rust? [Ency. p. 1048. Fr. La Nielle. Germ. Der Mehlthau. Span. El Tizon.

Obs. This is the Fungus which, under the name of Mildew (and perhaps Rust-though this may be another species,) often appears so abundantly and operates so injuriously, on our Wheat crops, in warm, close, foggy, and cloudy or wet weather, near harvest time,especially where the crop is a little backward, and mingled with an undue proportion of other grasses, or herbage. The species of this genus are numerous,-and appear to be confined to certain plants, from which they derive their specific names;-as P. Rosae-P. Rubi -P. Pruni-P. Trifolii, &c.

There may, perhaps, be different kinds of these minute Fungi (species of Aecidium, and other genera), infesting the various Grasses, and cultivated crops. A little orange-colored one is very prevalent, some seasons, on the leaves of the Washington Thorn (Crataegus cordata, Ait.). Until they shall be better understood, and a preventive remedy discovered, they deserve to be carefully studied, both by Naturalists and Farmers.

ORDER CLXX. ALGAE. Juss.

Leafless flowerless plants, with no distinct axis of vegetation, growing in water, and consisting either of simple vesicles lying in mucus, or of articulated filaments, or of lobed fronds formed of uniform cellular tissue,-absorbing the ambient liquid only by the immersed portion and not conveying it to the other parts; sometimes reddish, sometimes green,-emitting oxygen gas when exposed under water to the sun. Reproductive matter either altogether wanting, or contained in the joints of the filaments, or deposited in thecae (of various form, size and position) caused by dilatations of the substance of the frond. Sporules with no proper integument,-in germination elongating in two opposite directions. An Order comprising more than 100 genera, some of which afford food-others medicine, and materials used in the arts;-but few of them of any importance in Agriculture, and those chiefly as a manure, in the vicinity of the Sea shore. The edible Swallow's nests, which are esteemed such a delicacy by the Chinese, are believed to be mainly constructed of a species of Seaweed.

250. FUCUS. Agardh. Endl. Gen. 119.
[Latinized from the Greek, Phukos, a Sea-weed.]

Frond flat or compressed (rarely filiform), dichotomous, coriaceous. Air vessels, when present, innate in the frond, simple, large. Receptacles mostly terminal, turgid, containing tubercles imbedded in mucus and filled with sporules and filaments.

1. F. VESICULOSUS, L. Frond flat, with a middle nerve or rib, linear, dichotomous, entire; vesicles spherical, innate upon the frond in pairs; receptacles terminal, compressed, turgid, mostly elliptical. Hook. Brit. Fl. 2. p. 267.

BLADDERY FUCUs. Vulgo-Sea-weed. Sea-wrack.

Fr. Varec. Germ. Der Meer-tang. Span. Fuco.

Obs. This and some other Sea-weeds are attached to submarine rocks, by leathery shield-like expansions; but are often torn loose, and thrown on shore in great quantities, by the agitation of the Sea. Being collected and burned, they leave an alkaline residuum, called Kelp,— which is said to be valuable as a manure-as well as an article of considerable commercial importance. The poor half-starved cattle, on the coast of Scotland, feed upon this Sea-weed, in times of scarcity; but in our country, such fodder is but little known. For an interesting notice of Kelp, see the Farmer's Encyclopaedia,-a highly valuable Repository of information in every department of Agriculture.

THE Plants enumerated in this work may be classified according to their character and properties, as follows:

[N. B. Those which are cultivated, in Italics.]

I. Plants yielding esculent Roots, Herbage, or Fruits, for Man.

II. Plants yielding Food exclusively, or chiefly, for Domestic Animals.

V. Plants employed in the Arts, in Commerce, in Domestic or. Rural Economy.

VI. Pernicious and troublesome Plants-to be expelled: The
eminently pernicious ones in SMALL CAPITALS.