The anatomy of plants with an idea of a philosophical history of plants, and several other lectures, read before the royal society / by Nehemjah Grew ...

CHAP. IV. Of the GERMEN, BRANCH, and LEAF.

THE Parts of the Germen and Branch, are the same with those of the Trunk; the same Skin, Cortical and Lignous Bodies, Insertment and Pith, hereinto propagated, and distinctly observable herein.

2. §. For upon Enquiry into the Original of a Branch or Germen, it appears, That it is not from the Superficies of the Trunk; but so deep, as to take, with the Cortical, the Lignous Body into it self: and that, not only from its Circumference, but from in Inner or Central Parts; So as to take the Pith in also. Divers of which Parts may commonly be seen to shoot out into the Pith; from which Shoots, the surrounding and more superi∣our Germens are originated; in like manner as the Succulent Part of the Lignous Body of the Trunk is sometimes principally from those Fi∣brous Shoots which run along the Pith in the Root.

3. §. The manner wherein usually the Germen and Branch are fram'd, is briefly thus: The Sap (as is said, Chap. 3.) mounting in the Trunk, will not only by its length, but by its breadth also, through the Insertions partly move. Yet, its Particles being not all alike qualified, in diffe∣rent degrees. Some are more gross and sluggish; of which we have the formation of a Circle of Wood only, or of an Annual Ring. Others are more brisk; and by these, we have the Germen propagated. For by the vigour of their own motion from the Center, they impress an equal tendency on some of the inner Portions of the Lignous Body next adja∣cent

to the Pith, to move with them. And since the Lignous Body is not entire, but frequently disparted; through these Dispartments, the said interiour Portions, upon their Nutrition, actually shoot; not only towards the Circumference, so as to make part of a Ring; but even beyond it, in order to the production of a Germen. And the Lignous Body thus moving, and carrying the Cortical along with it; they both make a force upon the Skin. Yet their motion being most even and gra∣dual, that force is such likewise; not to cause the least breach of its parts, but gently to carry it on with themselves; and so partly, by the extension of its already existent parts, as of those of Gold in draw∣ing of Guilded Wyer; and partly, by the accretion of new ones, as in the enlarging of a Bubble above the Surface of the Water; it is ex∣tended with them to their utmost growth. In which growth, the Germen being prolonged, and so displaying its several parts, as when a Prospective or Telescope is drawn out, thus becomes a Branch.

4. §. The same way as the propagation of the Parts of a Germen is contriv'd, is its due nutrition also. For being originated from the inner part of the Lignous Body, 'tis nourished with the best fermented Sap in the Trunk, sc. that next adjacent to it in the Pith. Besides, since all its Parts, upon their shooting forth, divaricate from their per∣pendicular, to a cross Line, as these and the other grow and thrive together, they bind and throng each other into a Knot: through which Knot the Sap being strain'd, 'tis thus, in due moderation and purity delivered up into the Branch.

5. §. And for Knots, they are so necessary, as to be seen not only where collaterl Branches put forth; but in such Plants also, as shoot up in one single Trunk; as in Corn. Wherein, as they make for the strength of the Trunk; so by so many percolations, as they are Knots, for the trasmission of the Sap more and more refined towards the Ear. So that the two general uses of Knots are, For fimer standing, and finer growth.

6. §. Lastly, as the due Formation and Nutrition of the Germen are provided for, so is its security also; which both in its position upon the Trunk, and that of its Parts among themselves, may be observed. The position of its Parts shall be considered in speakimg of the Leaf. As to its standing in the Trunk, tis alwayes betwixt the trunk or older Branch, and the Basis of the Stalk of a Leaf; where∣by it is not only guarded from the Injuries of any contingent Vio∣lence; but also from the more piercing assaults of the Cold; so long, till in time 'tis grown larger, and more hardy. The maner and uses of the position of every Germen, considered as after it be∣comes a Branch; hath already been, by the Ingenious Mr. Sharrock very well observed; to whom I refer.

7. §. UPON THE prolongation of the Germen into a Branch, its Leaves are thus display'd. The Parts whereof are substantially the same with those of a Branch. For the Skin of the Leaf, is only the ampliation of that of the Branch; being partly by the accretion of new, and partly the extention of its already existent parts, dilated (as in making of Leaf-Gold) into its present breadth. The Fibres or Nerves dispersed through the Leaf, are only the Ramifications of the Branch's Wood, or Lignous Body. The Parenchyma of the Leaf,

which lies betwixt the Nerves, and as in Gentlewomens Needle-works, fills all up, is nothing else, but the continuation of the Cortical Body, or Parenchymous part of the Barque from the Branch into it self, as in most Plants with a thick Leaf, may easily be seen.

8. §. The Fibers of the Leaf neither shoot out of the Branch, or the Trunk, nor stand in the Stalk, in an even Line; but alwayes in either an Angular or Circular posture; and usually making either a Triangle, or a Semi-Circle, or Chord of a Circle; as in Cichory, Endive, Cabbage, &c. may be observed. And if the Leaf have but one main Fi∣ber, that also is postur'd in a bowed or Lunar Figure; as in Mint and others. The usual number of these Vascular Threds or Fibres is 3, 5, or 7.

9. §. The reason of the said Positions of the Fibers in the Stalk of the Leaf, is for its more Erect growth, and greater Strength: which, were the position of the said Fibers in an even Line, and so the Stalk it self, as well as the Leaf, flat; must needs have been defective; as from what we have said of the Circumferential posture of the Lignous Body in the Trunk, we may better conceive.

10. §. As likewise for the security of its Sap: For by this means it is, that the several Fibers, and especially the main or middle Fiber of the Leaf, together with a considerable part of the Parenchyma, are so disposed of, as to jut out, not from its upper, but its back, or neither Side. Whence the whole Leaf, reclining backward, becomes a Canopy to them, defending them from those Injuries which from colder Blasts, or an hotter Sun, they might otherwise sustain. So that by a mutual benefit, as These give suck to all the Leaf, so that again protection to These.

11. §. These Fibers are likewise the immediate Visible Cause of the Shape of the Leaf. For if the nethermost Fiber or Fibers in the Stalk (which thence runs chiefly through the length of the Leaf) be in pro∣portion greater, the Leaf is long; as in Endive, Cichory, and others: If all of a more equal size, it spreads rounder, as in Ivy, Doves-foot, Colts foot, &c. And although a Dock-Leaf be very long, whose Fibers notwithstanding, as they stand higher in the Stalk, are disposed into a Circle all of an equal size; yet herein one or more peculiar Fibres, standing, in or near the Center, betwixt the rest, and running through the length of the Leaf, may be observed.

12. §. In correspondence also to the size and shape of these Fibres, is the Leaf flat. In that either they are very small, or if larger, yet they never make an entire Circle or Ring; but either half of one, as in Borage, or at most three parts of one, as in Mullen, may be seen. For if either they were so big, as to contain, or so entire, as perfectly to include a Pith, the Energy of the Sap in that Pith, would cause the said Lignous Ring to shoot forth on every side, as it doth in the Root or Trunk: But the said Fibers being not figur'd into an entire Ring, but so as to be open; on that hand therefore where open they cannot shoot any thing directly from themselves, because there they have nothing to shoot; and the Sap having also a free vent through the said opening, against that part therefore which is there∣unto oppsite, it can have no force; and so neither will they shoot forth on that hand; and so will they consequently, that way only, which the force of the Sap directs, which is only on the right and left.

13. §. The several Fibers in the Stalk, are all Inosculated in the Leaf, with very many Sub-divisions. According as these Fibers are Inosculated near, or at, or shoot directly to the edge of the Leaf, is it Even, or Scallop'd. Where these Inosculations are not made, there we have no Leaves, but only a company of Filaments; as in Fennel.

14. §. To the Formations of Leaves, the Fouldings immediately follow. And sometimes they have one Date, or are the contemporary works of Nature; each Leaf obtaining its distinct shape, and proper posture together; both being perfect, not only in the outer, but Cen∣tral and minutest Leaves, which are five hundred times smaller than the outer: both which in the Cautious opening of a Germen may be seen.

15. §. Nor is there greater Art in the Forms, than in the Foulds or Postures of Leaves; both answerably varying, as this or that way they may be most agreeable. Of the Quincuncial posture, so amply in∣stanc'd in by the Learned Sir Thomas Brown, I shall omit to speak. Others there are, which though not all so universal, yet equally ne∣cessary where they are, giving two general advantages to the Leaves, Elegancy and Security, sc. in taking up, so as their Forms will bear, the least room; and in being so conveniently couch'd, as to be capable of receiving protection from other Parts, or of giving it one to ano∣ther; as for instance,

16. §. First, There is the Bow-Lap, where the Leaves are all laid somewhat convexly one over another, but not plaited; being to the length, breadth and number of Leaves most agreeable; as in the Buds of Pear-tree, Plum-tree, &c. But where the Leaves are not so thick set, as to stand in the Bow-Lap, there we have the Plicature, or the Flat-Lap; as in Rose-Tree, Strawberry, Cinquefoyl, Burnet, &c. For the Leaves being here plaited, and so lying in half their breadth, and divers of them thus also collaterally set together; the thickness of them all, and half their breadth, are much alike dimensions; by which they stand more secure within themselves, and in better consort with other Germen-Growths in the same Truss. If the Leaves be much in∣dented or jagg'd, now we have the Duplicature; wherein there are divers Plaits in one Leaf, or Labels of a Leaf, but in distinct Sets, a lesser under a greater; as in Souchus, Tansey, &c. When the Leaves stand not collaterally, but single; and are moreover very broad; then we have the Multiplicature; as in Gooseberries, Mal∣lows, &c. the Plaits being not only divers in the same Leaf, but of the same Set continuant, and so each Leaf gather'd up in five, seven or more Foulds, in the same manner as our Gentlewomens Fans. Where either the thickness of the Leaf will not permit a Flat-Lap, or the fewness of their number, or the smalness of their Fibers, will allow the Rowl, there This may be observed. Which is sometimes single, as in Bears-Ears, Arum, Flammula, Jerusalem Cowslip, &c. Sometimes dou∣ble, the two Rowls beginning at each edge of the Leaf, and meeting in the middle. Which again, is either the Fore-Rowl, or the Back-Rowl. If the Leaf be design'd to grow long, now we have the Back-Rowl, as in Docks, Sorrels, and the rest of this Kindred: as also in Primrose, and other like Plants. For the main Fibers, and there∣with a considerable part of the Cortical Body standing prominent from the Back-side of the Leaf, they thus stand securely couch'd up be∣twixt

the two Rowls; on whose security the growth of the Leaf in length depends. But those of Bears-Ears, Violets, Doves Foot, Warden, and many more, upon contrary respects, are rowled up in∣wards. Lastly, there is the Tre-Rowl, as in Fern; the Labels where∣of, though all rowled up to the main Stem, yet could not stand so firm and secure from the Injuries either of the Ground or Weather, unless to the Rowls in breadth, that by the length were super-induc'd; the Stalk or main Stem giving the same Protection here, which in other Plants by the Leaves, or some particular Mantling, is contriv'd. These, and other Foulds, See in the Figures belonging to the First Part of the Fourth Book.

17. §. According to the Form and Foulding of every Leaf or Germen, is its Protection order'd; about six ways whereof may be observ'd; sc. by Leaves, Surfoyls, Interfoyls, Stalks, Hoods and Mant∣lings. To add to what we have above given, one or two Instances. Every Bud, besides its proper Leaves, is covered with divers Leafy Pannicles or Surfoyls; which, what the Leaves are to one another, are that to them all: For not opening except gradually, they admit not the Weather, Wet, Sun or Aer, to approach the Leaves, except by degrees respondent, and as they are gradually inur'd to bear them. Sometimes, besides Surfoyls, there are also many Interfoyls set betwixt the Leaves, from the Circumference to the Center of the Bud; as in the Hasel. For the Fibres of these Leaves standing out so far from a plain surface; they would, if not thus shelter'd, lie too much expos'd and naked to the Severities of the Weather. Where none of all the Protections above-named, are convenient, there the Membranes of the Leaves by continuation in their first forming (together with some Fi∣bres of the Lignous Body) are drawn out into so many Mantles or Veils; as in Docks, Snakeweed, &c. For the Leaves here being but few, yet each Leaf and its Stalk being both exceeding long; at the bottom whereof the next following Leaf still springs up; the form and posture of all is such, as supersedes all the other kinds of Protecti∣on, and so each Leaf apart is provided with a Veil to it self. These, and other Protections, See in the Figures belonging to the First Part of the Fourth Book.

18. § The Uses of the Leaves, I mean in respect of their service to the Plant it self, are these: First, for Protection; which, be∣sides what they give one to another, they afford also to the Flower and Fruit. To the Flower in their Foulds; that being, for the most part, born and usher'd into the open Aer by the Leaves. To the Fruit, when afterwards they are display'd, as in Strawberries, Grapes, Rasps, Mulberries, &c. On which, and the like, should the Sun-Beams immediately strike, especially while they are young, they would quite shrivel them up; but being by the Leaves screened off, they impress the circumjacent Aer so far only as gently to warm the said Fruits, and so to promote their Fermentation and Growth. And accordingly we see, that the Leaves above-named are exceeding large in propotion to the Fruits: whereas in Pear-trees, Apple-trees, &c. the Fruit being of a solider Parenchyma, and so not needing the like protection, are usually equal with, and often wider in Diameter than the Leaves.

19. §. Another use is for Augmentation; or, the capacity for the due spreading and ampliation of a Tree or other Plant, are its, Leaves. For herein the Lignous Body being divided into small Fibres, and these running all along their lax and spongie Parenchyma; they are thus a Body sit for the imbibition of Sap, and easie Growth. Now the Sap having a free reception into the Leaves, it still gives way to the next succeeding in the Branches and Trunk, and the voyding of the Sap in these, for the mounting of that in the Root, and ingress of that in the Ground. But were there no Leaves to make a free reception of Sap, it must be needs be stagnant in all the Parts to the Root, and so the Root being clogg'd, its fermenting and other Offices will be voyded, and so the due Growth of the whole. As in the mo∣tion of a Watch, although the original term thereof be the Spring, yet the capacity for its continuance in a due measure throughout all the Wheels, is the free and easie motion of the Ballance.

20. §. Lastly, As the Leaves subserve the more copious advance∣ment, so the higher purity of the Sap. For this being well fermen∣ted both in the Root, and in its Ascent through the Trunk, and so its Parts prepar'd to a farther separation; the grosser ones are still deposited into the Leaves; the more elaborate and essential only thus supplied to the Flower, Fruit and Seed, as their convenient Ali∣ment. Whence it is, that where the Flowers are many and large, in∣to which the more odorous Particles are copiously receiv'd, the green Leaves have little or no smell; as those of Rose-tree, Carnations, French-Marigold, Wood-bind, Tulips, &c. But on the contrary, where the Flowers are none, or small, the green Leaves themselve are likewise of a strong savour; as those of Wormwood, Tansie, Baum, Mint, Rue, Geranium Moschatum, Angelica, and others.

An Appendix. Of Thorns, Hairs and Globulets.

THorns are of two kinds, Lignous and Cortical. Of the first are such as those of the Hawthorn, and are constituted of all the same substantial Parts whereof the Germen or Bud it self, and in a like proportion: which also in their Infancy are set with the resem∣blances of divers minute Leaves. Of affinity with these are the Spinets or Thorny Prickles upon the Edges and Tops of divers Leaves, as of Barbery, Holly, Thistle, Furze, and others; all which I think are the filamentous extremities of the Lignous Body sheathed in the Skin. But this principal differnce betwixt a Bud and these Lignous Thorns, is ob∣servable; That the Bud hath its Original from the Inner part of the Lignous Body, next the Pith: But these Thorns, from the outer, and less fecund Part; and so produceth no Leaves, but is, as it were, the Mola of a Bud.

2. §. Cortical Thorns are such as those of the Rasberry Bush, be∣ing not, unless in a most extraordinary small and invisible proportion propagated from the Lignous Body, but as, it seems, wholly from the Cortical and Skin, or from the exteriour part of the Barque.

3. §. The Growth of this Thorn may farther argue what in the Second Chapter we supposed; sc. That as the proper Tendency of the Lignous Body, is to Ascend; so of the Cortical to Descend. For as the Lignous Thorn, like other Parts of the Trunk, in its Growth ascends; This, being almost wholly Cortical, pointeth downdward. The use of Thorns the Ingenious Mr. Sharrock hath observed.

4. §. Upon the Leaves of divers Plants two Productions shew themselves, sc. Hairs and Gloubulets. Of Hairs, only one kind is taken notice of; although they are various. Ordinarily they are of a Simple Figure; which when fine and thick set, as on most Hairy Buds; or fine and long, as on those of the Vine, we call them Down.

5. §. But sometimes they are Branched out, from the bottom to the top, reciprocally on every side, in some resemblance to a Stags Horn; as in Mullen. And sometimes they are Astral, as upon Lavender, and some other Leaves, and especially those of Wild Olive; wherein every Hair rising in one round entire Basis a little way above the surface of the Leaf, is then disparted, Star-like, into several, four, five or six Points, all standing at right Angles with the said perpendicular Basis.

6. §. The Uses of Hairs are for Distinction and Protection. That of Distinction is but secondary, the Leaves being grown to a conside∣rable size. That of Protection is the prime, for which they were ori∣ginally form'd together with the Leaves themselves, and whose ser∣vice they enjoy in their Infant-estate: For the Hairs being then in form of a Down, always very thick set, thus give that Protection to the Leaves, which their exceeding tenderness then requires; so that they seem to be vested with a Coat of Frize, or to be kept warm, like young and dainty Chickens, in Wool.

7. §. Globulets are seen upon Orach, both Garden and Wild; and yet more plainly on Mercury or Bonus Henricus. In these, grow∣ing almost upon the whole Plant, and being very large, they are by all taken notice of.

8.§. But strict Observation discovers, that these Globulets are the natural and constant Off-spring of very many other Plants. Both these Globulets, and likewise the diversity of Hairs, I find that Mr. Hook hath also observed. I take notice, that they are of two kinds; Transparent, as upon the Leaves of Hysop, Mint, Baume, and many more White, as upon those of Germander, Sage, and others. All which, though the naked Eye will discover, yet by the help of Glasses we may observe them most distinctly. The use of these we suppose the same, in part, with those of the Flower, whereof we shall speak.

Notes

• Hist. of the Prop. of Veget.
• Tab. 4. f. 2. to f. 11.
• C. 3. §. 24.
• Tab. 4.
• Tab. 4.
• Treat. of the Quincunx.
• C. 2. §. 25.
• Hist of the Prop. of Veget.
• Micrography.