at least, if not scientific authority. In the ninth book of Milton's sublime poem, part of an address from Eve to Adam is to this effect:

Let us divide our labours, thou where choice

Leads thee, or where most needs, whether to wind
The woodbine round this arbour, or direct

The clasping ivy where to climb, while I

In yonder spring of roses intermix'd

With myrtle, find what to redress till noon.

Following this idea, therefore, we have next,

25. CAULIS amplectens, a clasping, or embracing stem (amplector, to embrace, Lat.)

Whether the fibres or tendrils of the stem and branches of ivy serve in any degree for its support, or not, one thing is very certain, that when it grows upon level ground it never produces the fructification, nor do its leaves undergo those changes in form which we shall attend to in another place. When it has a firm upright body as a tree, wall, or rock, to ascend, it grows with great luxuriance, and sometimes acquires a very considerable thickness* ; but I have never seen it thicker than a twig when growing without support.

For when the oak denies her stay,

The creeping ivy winds her humble way;
No more she twists her branches round,

But drags her feeble stem along the barren ground.†

* Malkin says of the castle at the village of St. Athans, Glamorganshire, that "the trunk of the ivy that encompasses the northern part of this castle, is of an uncommon substance. It at least girts five feet, and in some years yields large quantities of gum." Malkin's South Wales, p. 130.

+ Lloyd's Ode to Genius.

TREE HOUSELEEK.

65

With respect to the rooting stem, we have an excellent example of it, illustrative of Martyn's definition, in the tree houseleek (Sempervivum arboreum), which grows on rocks on the sea-shore of the Mediterranean, the branches or minor stems of which, after leaving the parent stock, make an abrupt bend downwards, throw out from the bent part a number of real radicles, and then become

In Lewis and Clarke's voyage up the Missouri, there is, also, an excellent example mentioned respecting a dwarf cedar, about three or four feet high, which spreads its limbs along the ground so as almost to conceal the latter, and from the under side of these limbs, roots, every here and there, shot into the earth, while the upper side was clothed with evergreen foliage and shoots.*

26. CAULIS Scandens, a climbing stem. (Scando, to climb, Lat.) A stem which ascends other plants,

&c. by means of tendrils. Observe a pea climbing up its rod, or a passion-flower, or a vine, and you will perceive that these vegetables are supported by a number of spiral threads which they protrude in various directions, and entwine round such bodies as they can approach. These threads are named cirri, tendrils or claspers, and will be attended to hereafter.

27. CAULIS volubilis, a twining stem.

Observe a hop ascending its pole, and you may remark that it is not supported on the latter either by fibres like the ivy, or tendrils like the vine; but simply by its own convolutions. It adheres as a snake would, by its folds.

While examining the hop, turn your face to the south; the east will then, of course, be on your left hand, and the west upon your right; and you know that the apparent motion of the sun is from east to west. Now you will perceive that the hop twines round the pole invariably from your left hand towards your right, that is, from east to west, or with the motion of the sun.

Examine next, a convolvulus, or a kidney-bean, and you will find that their stems as invariably turn from the west by the south towards the east; that is, from your right hand to your left, or against the motion of the sun. *

* See Martyn's Language of Botany, art. twining stem; but there is a mistake in the examples there cited, those being represented as twining against the sun, which twine with it, and vice versa.

CLIMBING PLANTS.

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It may seem strange, but nothing is more true, than that twining stems are governed in their direction by constant laws. No such stem twines indifferently from right to left, or from left to right; but each species has its own natural and irresistible tendency; and when it is by force diverted from that, it becomes sickly, and at length perishes.

Sinistrorsum (of which this is the sign ( ) means from left to right; and

Dextrorsum (D), from right to left.

Hence, CAULIS volubilis sinistrorsum (or CAULIS volubilis) means a stem twining from left to right or with the sun; and CAULIS volubilis dextrorsum (c. v. )), a stem twining from right to left, or against the sun.

Though in these islands we have many scandent and twining plants, yet we must turn our view to tropical countries, before we shall be fully able to comprehend their importance. Here, we seldom find them reaching higher than the top of a hedge; but in tropical regions they mount to the summits of the highest trees, and sometimes, by their weight, when a tree is standing alone, bring it to the earth. The climbing and voluble plants of Jamaica, especially the convolvuli, abound so much in reclaimed lands that have been suffered to run wild again, that it is necessary to cut one's way through them with a bill-hook.* In forests they

* Vide Sloane's Jamaica. A similar impediment occurs in many other countries, e. g. "It was difficult to get far into the Java forests, from the quantity of underwood, and the

serve to bind the trees together, and this may perhaps on many occasions prevent the latter being upset in storms. Bartram describes the Grape - vines, the twining Zizyphus (Rhamnus volubilis), the ash-leaved trumpet-flower, (Bignonia radicans), the cross-bearing trumpet-flower (Bignonia crucigera), and other climbing vegetables, as tying together the trees in the forests of Carolina and Georgia, with garlands and festoons, which form enchanting shades. This author observes of the grape vines, that "from their bulk and strength, one would imagine they are combined to pull down those mighty trees to the earth, when in fact, amongst other good purposes, they serve to uphold them. They are frequently nine, ten, and twelve inches indiameter, and twine round the trunks of the trees, climb to their very tops, and then spread along their limbs from tree to tree throughout the forest."

In some of the woods and swamps of America, the laurel-leaved smilax (Smilax laurifolia) forms a most troublesome obstacle to persons passing. It runs, by means of its cirri, up trees and bushes, and extends from one to another so as to bar all

vast number of creeping plants, which form a sort of net supported by other trees, and are impassable without an instrument to cut them. Some of them were likewise of great strength. One trailed along the ground, in the manner of some of the convolvulus kind, with a stalk about an inch in diameter throughout, and of a length exceeding a hundred feet."-Staunton's Embassy, vol. i. p. 301.

* Travels, p. 85.