« 上一頁繼續 »
Fig. 106 shews the same plant in its natural size; a, is the stem, which is a cylindric and jointed culm. At b, is the leaf, which is long, narrow, pointed, simple, and entire. At c, are the flowers, which are thick, panicled and terminal.
The orchard grass is very common in the New England and Middle States.
Of all the grasses, the darnel (Lolium), only, is poisonous ; this seemed to have been avoided in the days of Virgil, who, in his “ Pastorals,” represents the shepherds as speaking of the lolium as destructive to their flocks.
The same number of stamens are 6 found in the plants of this class, as in
those of the 13th class, Didynamia. In the fourth class the stamens are of equal length, but in the thirteenth they grow in two pairs of unequal length.
Order Monogynia. As an example of this order, may be mentioned the HousTONIA cærulea, which is known by different common names; in some sections of the country it is called Innocence, in others Venus' Pride, and in some Blue Houstonia. It is a very delicate little flower, appearing early in the spring, in grassy fields and meadows; the colour varies from sky blue (which gives its specific name cærulea) to a pure white. The flower has a small calyx, with four divisions; a monopetalous corolla of four divisions, which gives it something the appearance of a cruciform plant.
The common Plantain (Plantago), (See Fig. 107, a) is found here; it is a plant by no means useless, although it exhibits nothing interesting to gratify the sight. The leaves are some. times used in external applications for medicinal purposes; they are also, when young and tender, boiled and used for food in some parts of the United States. The flowers of the plantain grow on a spike; they are very small, but each one has a ca. lyx and corolla ; these are both four-parted ; the filaments are
Analysis of the orchard grass-How does the fourth class agree with, and how differ from the thirteenth class -Houstonia-Plantain.
very long, and the pericarp is ovate with two cells. Canary birds are very fond of the seeds of the plantain.
Aggregate flowers. We find in this class the aggregate flowers (aggregatæ), or such as have many flowers on the same receptacle; they have a general resemblance to the compound flowers of the class Syngenesia, but differ from them in having but four stamens with anthers separate, while the Syngenesious plants have five united anthers. The aggregate flowers are not often yellow, like many of the compound flowers, but are usually either blue, white, red, or purple. The Button bush (Cephalanthus), of about five feet in height, affords a good ex. ample of the natural order aggregata. The inflorescence is white, appearing in heads of a globular form, each consisting of many little perfect florets ; each head has its own 4 cleft calyx, but there is no general calyx, or involucrum for the whole. Only one species of this genus, the occidentalis,* is known, and this is entirely confined to North America. The Teasel (Dipsacus), belongs to the aggregate flowers; its inflorescence is in heads of the form of a cone; it is furnished with narrow, stiff leaves in the wild Teasel; in the species which is cultivated these bristly leaves are hooked; on this account they are used by clothiers to raise a nap or furze on woollen cloth. The Cornus, so called from a Latin word cornu, a horn, on account of the hardness of the wood, is a genus composed mostly of shrub-like plants, with flowers growing in flat clusters or cymes, like the elder. The florida, a species of Cornus, often called Box-wood, sometimes Dog-wood tree, is a beautiful ornament of our woods. It may be considered either a large shrub or a small tree; it grows from the height of fifteen to thirty feet. Its real corollas are very small, and are clustered together in the manner which is called, in botany, an aggregate.
This aggregate of flowers is surrounded by that kind of calyx called an involucrum, which, in this plant, consists of four very large leaves, usually white, but sometimes of a pale rose colour ; to the latter circumstance is owing its specific name florida, or florid. You would, no doubt, on the first sight of this plant, mistake the large leaves of the involucrum for the petals. At Fig. 107, b, is the representation of the cornus; the style is about the same length as the petals ; these are four in number, oblong and equal.
At c, Fig. 107, is the Cissus,t or false grape; its calyx is * From occidens, the west, being found on the western continent.
† Mirbel gives this name to the plant whose flower is here described, and places it in the class Tetrandria. Eaton, on good authority, names it Ampelopsis, and puts it in the class Pentandria ; although it may occasionally be found
very small (not, seen in the cut); the petals are spreading and reflexed; the filaments are shorter than the petals, and crowned with large heart-shaped anthers.
Another very common genus of the class Tetrandria, is the Bed-straw (Galium), an herbaceous plant, with very small white flowers; the leaves grow in whorls; in different species, the leaves thus clustered together stand around the stem in fours, fives, sixes and eights. Some species exhibit a peculiar roughness upon the stems and leaves. This genus, with many others of the class, belongs to the natural order Stellatæ,* or starry plants ; the leaves radiating from the stem as rays of light from a star.
Among the exotics of this class, are the SANTALUM, which produces the sandalwood, and the Madder (Rubia tinctoria), the root of which produces a beautiful scarlet colour. The latter plant is said to have the singular property of tinging, with its red colour, the bones of the animals that feed upon it. This is one of the starry plants, belonging to the farnily Stellatæ of Linnæus ; Jussieu has arranged this, and some of the plants whose leaves grow in whorls, under his 57th order, Rubiaceæ. The Silver tree (PROTEA argentea), has soft leaves, resembling satin, of a silver colour. Another species of Protea, the aurea, has gold coloured leaves, which are edged with scarlet. Both these trees are natives of the Cape of Good Hope, and have never been found in any other locality.
Order Tetragynia. We find here the holly (Ilex); this is an evergreen, with a smooth, greyish bark, shining, thorny leaves, whitish flowers, and scarlet berries; this plant is very common in England for fences; its verdure is not impaired by the most severe winter.
with five stamens, its four petals and the four divisions of its calyx, seem to indicate that the fifth stamen is but an accidental circumstance; this seems to have been the opinion of Mirbel and some others.
* From stella, a star.
The class which we are about to examine, is said to comprehend more than one tenth part of all known spe. cies of plants. It differs from the class Syngenesia in having its five stamens separate, while the Syngenesious plants have the same number of sta. mens united by means of their an. thers. Plants with five stamens, including those which have anthers united, are said to constitute one fourth part of the vegetable kingdom.
Order Monogynia. There are six orders in the class Pentandria, the first of which, Monogynia, is large and important. Here we find the 41st natural order of Linnæus, the Asperifolia, a name derived from two Latin words, asper, rough, and folium, leaf, signifying rough leaved plants. These have monopetalous corollas, with five stamens and five naked seeds. The seeds are dicotyledons; this natural family is found in the 8th class of Jussieu, and by him is called boraginea from the genus Borago. “The change in the corolla of these plants, in general, from a bright red to a vivid blue as the flower expands, apparently caused by the sudden loss of some acid principle, is a very curious phenomenon."*
The Cynoglossum is perhaps as common as any of the asperifolia or rough leaved plants. Its common name is hound's tongue, so called from its soft oval leaves, which are thought to resemble the tongue of a dog. Although the Cynoglossum is classed with the rough leaved plants, its leaves are remarka. bly soft, appearing to the touch like velvet ; it is about two feet high, the flowers are of a reddish purple, growing in panicles.t The Lungwort (Pulmonaria), which also belongs to this natural
It is said that the leaves of this plant, if strewed about apartments infested with rats and mice, will expel these vermin.
Class Pentandria—How different from the class Syngenesia-Order Monogynia-Describe the characters of the family Asperifolia-Mention the principal genera in this family.
family, has two species in North America with smooth leaves. The Mouse-ear (Myosotis), is valued for its medicinal properties; a species, the arvernis or Forget-me-not, is an interesting little blue flower. The Gromwell (Lithospermum), is a rough plant with white flowers; the bark of the plant contains so much silex or flinty matter, as to injure the sickles of the
reapers, when it grows in the field with the grain. The name Litho. spermum, is from the Greek lithos, a stone, and sperma, a seed, in allusion to the hardness of the seeds. The Borago, which gives its name to Jussieu's Natural family, including rough leaved plants, is an exotic, very common to our gardens. The corolla is wheel-shaped, of a beautiful blue colour, having its throat closed with five small protuberances; the same is obser. vable in the cynoglossum and some others of this class; the stamens are attached to the tube of the corolla ; you must take off the corolla carefully and you will see both the little scales which choked up the throat of the corolla, and the manner in which the five stamens grow to it.
The Luride, from lurid, signifying pale or livid, are in the 28th natural order of Linnæus ; this order is by Jussieu inclu. ded under his 41st, the Solaneæ. The general characters of these plants are, monopetalous corollas, of a lurid or pale ap. pearance; five stamens attached to the base of the corolla, and alternating with its divisions; the leaves are alternate. The common Potatoe (SOLANUM tuberosum), is of this natural family; the flowers of this plant are large and the organs very plain for analysis. There is a peculiarity in the appearance of the anthers which it is well to notice ; they are of an oblong form, thick and partly united at the top, forming a cone, and instead of opening at the side, as anthers usually do, they open at the top by two pores. The potatoe was not known in Europe, until after the discovery of America. In the year 1597 Sir Walter Raleigh on his return from this country, distributed a number of potatoes in Ireland, where they became numerous, and the cultivation of them soon extended into Eng. land. It is said that the root of the potatoe is white or red according to the colour of the flower. The little green balls, upon the stalks of the potatoe, are the pericarps, and contain the seed; but this plant is usually produced from the root. The little knobs or eyes which you may notice upon the potatoes, are each one a kind of germ or bud ; and in planting potatoes the whole root is not put into the ground, but cut into as many pieces as there are eyes, each one of which, produces
Luridæ or Lurid plants---Potatoe.