The class Diccia (two houses) has staminate and pistillate flowers on separate plants. The distinction with regard to the orders, as in the preceding class, is derived from the number of

stamens.

There are no plants of the first order, or with one stamen.

Order Diandria.

The 2d Order contains the willow, (SALIX,) which has long and slender aments, both of staminate and pistillate flowers, the two kinds being on separate trees.

The order TRIANDRIA contains the fig, (Ficus,) remarkable for containing the flower within the fruit; this is botanically considered as a juicy receptacle, within which are concealed the minute flowers and seeds. The fig is peculiar to warm countries.

TETRANDRIA Contains a parasitic plant, the Mistletoe; only one species is indigenous to this country. The Druids* considered this plant as sacred to the sylvan deities. Tradition relates, that where Druidism prevailed, the houses were decked with this plant, that the sylvan spirits might repair to them.

The order PENTANDRIA Contains the hemp, hop, &c. Fig. 150 represents the pistillate and staminate flowers of the hemp, (Cannabis sativa ;) at a, is the barren or staminate flower, containing five stamens, and having its calyx deeply five-parted; the corolla is wanting. At b, is a fertile or pistillate flower with its calyx opening laterally; e, shows the same flower divested of its calyx; the seed is a nut, which is crowned with two styles. The hemp belongs to the natural order Urticeæ, (from Urtica, a nettle ;) the fibres of its stems are manufactured into cloth, cordage, and thread. The hop produces its fertile flowers in large cones formed of membranous, imbricated scales; these flowers have a peculiar odour, which is said to produce a narcotic effect upon the brain. The use of the flowers of the hop to produce fermentation in beer are well known. This plant contains a small portion of the nitrate of potash, (saltpetre.) HEXANDRIA Contains the honey-locust and green-brier.

OCTANDRIA has the poplar, (POPULUS,) similar in natural character to the willow.

MONADELPHIA, or the 15th order, contains the red-cedar and the yew, which belong to the cone-bearing family, with the pine and cypress. We have now completed our remarks upon two classes which have imperfect flowers. Our review of these has been brief, when compared to the many interesting facts which presented themselves, in association with the various important plants which we have passed in rapid succession.

The Druids, it is supposed, derived their name from drus, a Greek word, signifying oak, as it was in groves of this tree that the priests celebrated their mysterious rites, and sacrificed human victims to their sanguinary deities.

Class Diccia-Willow-Fig-Mistletoe-Hemp-Hop-Order Hexandria-Octandria-Monadelphia.

17

Fig. 151.

LECTURE XXXVII.

CLASS XXI.-CRYPTOGAMIA.

THE twenty preceding classes include the Phenogamous plants; we are now to consider the Cryptogamous class;-we here find the stamens and pistils either wholly concealed from observation, or only manifest upon the strictest scrutiny. These plants constitute the first class of Jussieu's method, called acotyledonous; their seed being destitute of any cotyledon.

As we proceed in this last of the Linnæan classes, we shall find all our former principles of arrangement fail us, and it might almost seem as if we had entered upon a new science. The class Cryptogamia includes all plants which do not find a place in some of the other classes.

Ferns, mosses, lichens, and mushrooms, constitute the principal part of this class. At Fig. 151, a, is a fern, of the genus Asplenium, which bears its fruit on the back of the fronds; at b, is a moss of the genus Hypnum, showing two of its flowers borne on slender pedicels; at c, is a genus of the Lichen family; at d, is the Agaricus, one of the most common of the mushrooms.

Some writer has said, that Linnæus, having arranged the plants which would admit of classification, took the remainder and cast them all into a heap together, which he called Cryptogamous;-he did not, however, rest satisfied in thus throwing them together, but subdivided this miscellaneous collection into orders; or we might more properly say, that he gave names to those divisions already marked out by nature.

Of these orders, which are natural families brought together on account of general resemblances and analogies, without reference to any one principle, there are six.

Order Filices, or Ferns.

The 1st Order contains the Ferns; their plume-like leaves are

called fronds. The fruit mostly disposed in dots or lines, grows on the back, summit, or near the base of the frond. At Fig. 152, is a delineation of some of the various modes in which the fructification of ferns appears; a, is the genus POLYPODIUM or polypody, with capsules in roundish spots on the back of the frond; b, ASPLENIUM, capsules in lines nearly parallel, diverging from the centre of the frond; C, BLECHNUM, capsules in uninterrupted lines running parallel to the midrib of the frond on both sides; d, PTERIS, or brake, capsules form ing lines on the edge of the leaf.

Some ferns bear their fruit in a peculiar appendage, as a spike or protuberance in the axils, or at the base of the leaves; no appear ance of flowers in these plants is ever presented. When the brown or white dust-like spots are examined with a microscope, they are found to consist of clusters of very small capsules, at first entire, but afterward bursting elastically and irregularly. Besides attention to the situation and form of the capsules, it is necessary to observe the membrane which envelopes them; this is called their involucrum.* The seed is as minute as the finest powder, and so light as to be wafted by the air to any distance or height; we thus often see ferns growing high on the trunks of trees, or on the summits of old buildings. Some ferns grow to a great height in southern latitudes, almost like trees. At the southern extremity of Van Diemen's Land, a species has been found, whose trunks attained to the height of twelve or sixteen feet. One species in our country, ONOCLEA sensibilis, called the sensitive fern, is said to wither on being touched by the human hand, though the touch of other substances does not produce the same phenomenon.

The number of species of ferns which are already known, amounts to about seven hundred. They generally abound in moist and shady situations, but are sometimes found on rocks and dry places, and on the trunks and branches of old trees. The frond, or leaf of the fern, is often pinnate, or divided like a feather; sometimes it is undivided, and resembles a palm-leaf.

The EQUISETUM hyemale is known to housekeepers under the name of scouring-rush. The quantity of silex contained in the cuticle, renders it a good substitute for scouring-sand.

Order Musci, or Mosses.

The 2d Order contains the mosses, which are little herbs with distinct stems; their conical, membranous corolla is called a calyptra, or veil, its summit being the stigma; this veil clothes the capsules, which before the seeds, called sporules, ripen, is elevated on a footstalk. The capsule, called theca, is of one cell, and one valve, opening by a vertical lid; the seeds are very numerous and minute. In some genera the veil is wanting, this serves as a distinction in the order. The barren flower of mosses consists of a number of nearly cylindrical, almost sessile anthers; the fertile flowers have one perfect pistil, seldom more, accompanied by several barren pistils. Both stamens and pistils are intermixed with numerous, succulent threads. You may here observe (Fig. 153) the different parts of mosses; a, represents the theca; b, the pedicel, or stem; c, the sheath, which,

* Also called indusium. The capsules are the thecæ; a collection of them, sori; the seeds are sporules.

Modes of the fructification of ferns-Sensitive fern--Number of species of fernsScouring-rush-Mosses-Explain Fig. 153.

theca is ripe, and has thrown off its other parts, often appear around its edge; g, the barren or staminate flower of a moss.

The mosses are generally perennial and evergreen, and capable of growing in colder climates than most other vegetables. In Spitzbergen, the rocks which rise from the surrounding ice are thickly clothed with moss. A botanist who travelled in Greenland, counted more than twenty different species of moss without rising from a rock where he was seated.

All the parts of the mosses which have been described, are not seen without the assistance of a good microscope. It is not to be expected that young botanists will be fond of this department of the science, although those who become acquainted with it, discover much enthusiasm in its pursuit. The following interesting remarks on Cryptogamous plants are taken from an English writer.

"Mosses and Ferns, by the inconsiderate mind, are deemed a useless or insignificant part of the creation. That they are not, is evident from this, that He who made them has formed nothing in vain, but on the contrary has pronounced all his creation to be good. Many of their uses we know; that they have many more which we know not, is unquestionable, since there is probably no one thing in the universe, of which we can dare to assert, that we know all its uses. Thus much we are certain of, with respect to mosses, that as they flourish most in winter, and at that time cover the ground with a beautiful green carpet, in many places which would otherwise be naked, and when little verdure is elsewhere to be seen; so at the same time, they shelter and preserve the seeds, roots, germs, and embryo plants of many vegetables, which would otherwise perish. They furnish materials for birds to build their nests with, they afford a warm winter's retreat for some quadrupeds, such as bears, dormice, and the like, and for numberless insects which are the food of birds and fishes, and these again the food or delight of men. Many of them grow on rocks and barren places, and by rotting away, afford the first principles of vegetation to other plants, which never else could have taken root there. Others grow in bogs and marshes, and by continual increase and decay, fill up and convert them into fertile pastures, or into peat-bogs, the source of inexhaustible fuel to the polar regions.

"They are applicable also to many domestic purposes. The Lycopodiums are some of them used in the dying of yarn, and in medicine; the Sphagnum (peat-moss) and Polytrichum, furnish convenient beds for the Laplanders, and the Hypnums are used in the ti

Mosses capable of enduring cold-Microscope necessary in examining mosses-Remarks of an English writer.

ling of houses, stopping crevices in walls, packing brittle wares, and the roots of plants, for distant conveyance.

"To which may be added, that all in general contribute entertainment and agreeable instruction to the contemplative mind of the naturalist, at a season when few other plants offer themselves to his view.

"The Fungi have been suspected by some to be, like sponges and corals, the habitations of some unknown living beings, and being alkaline, have been classed in the animal kingdom; but they are known to produce seeds, from which perfect plants have been raised; and the celebrated Hedwig, by great dexterity of dissection, and by using microscopes of very highly magnifying powers, assures us that he has discovered both stamens and pistils, not only in this order of plants, but in the other orders of the Cryptogamous family."*

Order Hepatica, or Liverworts.

The 3d Order contains the Liverworts, which are more succulent or juicy than the mosses; they have four-valved thecæ, which circumstance, and that of their not opening with a lid, distinguish them from the mosses. Their name, Hepatica, signifies liver; but it is not yet known whether they received that name on account of some supposed virtue in curing diseases of the liver, or whether it was because they were thought to resemble the lobes or divisions of that organ. One of the most common genera of this order is the Junger mannia; you may here see (Fig. 154) a species of this, the compla nata, with its parts, as represented under a magnifier.

α

Fig. 154.

a, is a plant of natural size, in fruit. b, the fruit magnified, showing the sheath, the peduncle rising from it, and the theca at top, not yet burst. c, the open capsule splitting and dis

charging the seeds. d, the theca empty, showing its four valves.

Order Algæ, or Sea- Weeds.

The 4th Order includes the sea-weeds and frog-spittle; these have leathery fronds, with fine dust-like seed, enclosed in inflated portions of the frond. They are almost always aquatics; generally green or reddish. One genus of this family is the Fucus. The Fucus natans, sometimes called the gulf-weed, is very abundant in the Gulf of Florida, and is found in various parts of the ocean, forming masses or floating fields, many miles in extent. The plant seems to possess no distinct root, though it perhaps originally vegetated on some seabeaten shore, from whence it was by accident thrown upon the ocean's wave.

The Fucus giganteus is said to have a frond of immense length; from whence its specific name, signifying gigantic. You are here

*Notwithstanding the weight which Thornton, author of the above quotation, gives to the opinion of Hedwig and others, it is, at present, much doubted by naturai. ists, whether the Fungi have organs analogous to stamens and pistils.

Describe Fig. 154-Liverworts-Derivation of the name-Sea-weeds-Fuci-Gulf. weed.