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. III. Of the Figure of the Leaf; and the Apparent Position of the Fibres.

THAT which in the Leaf offers it self next to be observed, is its Figure. This is infinitely va∣ried with the several Kinds of Plants: and there are some, which have Leaves (besides the two first Dissimilar ones) of Two Kinds or Two di∣stinct Figures; as the Bitter-Sweet, the com∣mon Little Bell, Valerian, Lady-Smocks, and others. For the Under Leaves of Bitter-Sweet, are Entire; the Upper, with two Lobes: the Under Leaves of the Little Bell, like those of Pancy; the Upper, like those of Carnation, or of Sweet-William. And in some Plants, Nature assecteth a Kind of Irregularity; the Leaves whereof are of no one certain Figure; as in Dragon, Peony, Bishops-Weed, &c.

2. §. BUT the Leaves of most Plants, have a Regular Figure; and this Regularity, both in Length and Circuit, always defineable. In Length; by the Proportion between the several Leaves upon one Stalk, or between the several Lobes upon one Leaf. So the Leaves of Clematis Sylv. major, which stand by Ternaries, shorten by equal Proportions, that is to say, if, the chief Fiber of each, be divided into equal Parts; their several Lengths are not as Ten, Eight, and Four; but as Ten, Eight, and Six. So the Lobes and Fibers of Clematis Virgini∣ana Hederae folio, of Artenuisa, &c. shorten in like manner by equal Proportions. The same is observable in measuring, upon a Gooseberry-Leaf, from the Poynt of the first Lobe, to the first Angle; from thence, to the second Poynt; from thence, to the second Angle; and from thence to the third Poynt.

3. §. But in many, the Proportion is different. So in the Leaves of the Lesser Maple; the shortning of the smaller Lobes, with respect to the middelmost; is not Equal, but Double to that of the middlemost, with respect to the Greater. For if their chief Fibres be divided into Equal Parts, they are as Eleven, Nine, and Five. On the contrary, in the Leaves of Althaea fruticosa Pentaphylloidea, the middlemost Lobes shorten by a greater Proportion than the Least; all three being as Ten, Fourteen, and Twenty.

4. §. WITH respect to the Circumserence, the Figure of most Leaves is very Complex. Yet Two things are evident. First, that all Regular Leaves, are desined or measured out by Circles; that is, by the Arches or Segments of several Circles, having either the same, or di∣vers Centers and Diameters. Secondly, That the Length of the Leaf, or of the chief Fiber thereof, is the Standard Measure for the Diame∣ters of these Circles: these being either its full Length, or certain equal parts substracted, or multiplied; as half its Length, or its Length and half, &c.

5. §. TO make this appear, I shall give several Instances: of some, where both the Edges are of one Measure; and of others, where they are different. And of both kinds, where they are measured by fewer, and where by more Circles.

6. §. The Leaf of Lagopus major fol. pennat. is measured by One Circle, the same on both Edges, whose Diametre is Thrice the Length of the Leaf.

7. §. That of Syderitis Salvia•• fol. by Two Circles: the Diameter of the Lower, being Twice the Length of the Leaf; of the upper, the Length and half. In both these the Circles are drawn Outward; that is, with their Centers some where upon the middlemost or chief Fiber of the Leaf.

8. §. That of Orange-Tree, is also measured by Two Circles: but one of them repeated with Opposite Centers. That next the Cone of the Leaf, is drawn Inward; that is, with the Center no where upon the Leaf, but without it. The Diameter hereof is just the Length of the Leaf. The midle part of the Edge is measured by the same Circle, only drawn Outward. The lower Circle next the Stalk, is drawn In∣ward, as the upper; and its Diameter Three times the Length of the Leaf.

9. §. The Leaf of the Venetian Vetch, is measured by Three Cir∣cles. That next the Cone, drawn Inward; the Diameter whereof, is Twice the Length of the Leaf; the next is drawn Outward; where∣of the Diameter, is just the Length. The third or lowermost, is drawn also Outward; and its Diameter, half the Length. So that they all lessen by an Equal Proportion.

10. §. The Leaf of Great Laserwort, is also measured by Three Circles; all drawn Outward, and one of them Repeated. The Diameter of that next the Cone, is Half the Length of the Leaf; of the next, Thrice the Length; of the Third, just the Length; the lower∣most, is the same with the First.

11. §. That of Broad Leav'd Laserwort, is also measured with Three Circles; and one of them repeated with Opposite Centers. The Diame∣ter of the First, is Half the Length of the Leaf; of the Second, Twice the Length; of the Third, just the Length: all of them drawn Out∣ward. That next the Stalk, is the same with the First; only drawn Inward.

12. §. The Figure of the Leaf of the Cornelian Cherry, is exactly that of the foregoing, Inverted: the same measure there beginning at the Base, and ending at the Cone; which here begins at the Cone, and ends at the Base: as by comparing their Draughts together may be ob∣serv'd.

13. §. IN ALL, the foregoing Examples, both the Edges of the Leaves have the same Measure. But they have oftentimes, different ones; as in these that follow.

14. §. The Leaf of Althaea fruticosa, is measured by Three Circles. The left Edge (as the Leaf lies with the backside upward) by One Circle, but Twice repeated. For the Diameter of the First, is the Length of the Leaf; the Second is the same, but drawn upon another Center; the Third also the same, but drawn Inward. The right Edg, is mea∣sur'd by Two Circles: the Diameter of the First, being the Length of the Leaf; of the Second, Half the Length.

15. §. That of Black Poplar, by Three; and each Edge by Three repeated. On the left, the Diameter of the First, is the Length of the Leaf; of the Second, Half the length; of the Third, the Length and Half. The Measure of the right Edge, is that of the left, Inverted: the same Measure there beginning at the Base, and ending at the Cone; which here begins at the Cone, and ends at the Base.

16. §. That of Doronicum, is measured by Three Circles, whereof, one is repeated Once; and another Thrice. The right Edge by Two, and One repeated. For the Diameter of the First or that next the Cone; is the Length of the Leaf; the next is the same, but drawn Outward; the Diameter of the Third, is Half the Length. The left Edge, by Three Circles; whereof One is repeated on the same Edge, and Two, the same, as on the other. For the Diameter of the first, is the Length of the Leaf; of the Second, Four times the Length; the Third, the same as the First; and of the Fourth, Half the Length.

17. §. Lastly, that of Mountain Calamint is measured by Four Circles. The left Edge, by Three Circles, of which, the lowermost is once repeated: the right Edge also by Two; whereof the nether is likewise once repeated.

18. §. It may seem, even from these Instances, no very unobvious Conclusion; That all Crooked Lines, Spiral, Helick, Elliptick, Hyperbo∣lick, Regular, or Irregular; are made up of the Arches of Circles, having either the same, or divers Centers and Diameters. And, as otherwise, so from the Contemplation of Plants, men might first be invited to Ma∣thematical Enquirys.

19. § TOGETHER with the Figure of the Leaf, the Position of the Fibers, as it is apparent before Diffection, is observable; especi∣ally on the back of the Leaf. Whereof I shall add, to what I have said in the First Book, the following Remarques.

20. §. First, that there are some Leaves, in which the first Colla∣teral Fibres make Right Angles with the Great one in the midle: as the Great-Maple, the Great Celandine, Chondrilla, and the rest, or many, of the Intybous Kind; with some few others. But that generally all the chief Fibers of a Leaf, make Accute Angles together: both where they stand collateral with the midle Fiber, as in Strawberry; and where they all part at the Stalk, as in Mallow.

21. §. Again, that of these, there are some few, any two of whose Defining Fibres making two Rays of equal Length, take in One Eighth Part of a Circle, as in Mallow; and in some one Tenth: but in most they take in either one Twelfth part, as in Holy-Oak; or one Sixth, as in Sirynga. So that where the Fibres stand Collateral with one in the the midle, if you suppose them to be drawn out at Opposite Angles; or where the chief Fibers part at the Stalk, you only take in the Stalk; you will thereby divide a Circle into Eight, Twelve, or Six equal Parts; as in Sirynga, the Vine and others. And so likewise, where there are several Sprigs upon one Stem, as in Fenil, Hemlock, and the like: as will best be understood by the Figures.

Notes

• Tab. 46.
• Tab. 46.
• Tab. 44.
• Tab. 44.
• Tab. 44.
• Tab. 45.
• Tab. 44.
• Tab. 44.
• Tab. 45.
• Tab. 45.
• Tab. 45.
• Tab. 45.
• Tab. 46, & 47.
• Tab. 46, 47.