HESE are Globular Excrescences, Spots, Hairs, Thorns and Prickles: of all which, except Spots, I have spoken in the Appendix to the Chapter of Leaves in the First Book.
2. §. Of the Globulets, it may here be further noted, That those which are white, and lie sometimes like a fine Powder upon the Leaf, were once transparent, as in Bears-Ear; their cleer Liquor being now evaporated to an Extract of White Flowers. Tab. 43. This, if licked off, will give you the Tast of the more Essential Content of the Plant; different from that perceived in chewing the Leaf.
3. §. For the observing of them, it may also be noted, That although they often grow on both sides the Leaf alike; yet sometimes, as in Ground-Ivy, only or chiefly on the Back-Side. And that in many Plants, where the elder Leaves have none; on the young Buds they are very numerous; as in Corin Tree, Sorrel, and others.
4. §. AS for Spots, the smaller ones are observable not only in St. Johns-worts, (in which Plant only they are commonly taken notice of) but also in Rue, Tab. 43. Ground-Ivy, Pympernel or Anagallis, and divers other Plants, when held up against the Light. The original whereof seems to be, at least in some, from the Globulets above mentioned; that is, when they break and dry away. So the Spots of Rue-Leaves, which in the Refection of Light look black, but upon the Trajection thereof are transparent; are so many little Holes, pounced half way through the thickness of the Leaf, and seem as made, by the breaking and drying away of as many Globulets. Whence also, as the Globulets are best seen in the younger Leaves, so these Spots in the elder.
5. §. BESIDES these, and some others (as those in Ladies-Thistle) which are Natural to the Leaf; there are also some Spots, or rather Streaks, which are Adventitious; as those in the Leaves of Sonchus. Tab. 43. The Cause whereof, is a small flat Insect, of a grey Colour, and about ⅙ᵗʰ of an Inch long. Which neither ranging in bredth, nor striking deep into the Leaf; eats so much only as lies just before it, and so runs scudding along betwixt the Skin and the Pulp of the Leaf; leaving a whitish Streak behind it, where the Skin is now loose, as the measure of its Voyage.
6. §. THE Original and several kinds of Thorns, I have describ’d in the above said Appendix. I only add, that the very Leaves of some Plants, if they stand till the second year, are changed into so many Thorns, as in the Furz.
7. §. They are of Use, not only for the Protection of the Bud; but likewise, for the support of the Plant; as is observable in those Climbers, which are neither strong enough to stand of themselves; nor yet, from their fragility, are capable of winding about another, without being torn all to pieces. For which end also, these Thorns grow not like Buds, erected; but poynt all downwards, like so many Tenters or Hanging-hooks: as in the Bramble, chiefly on the Stalks; and in Clivers, Tab. 43. also on the Leaves themselves; whereby they catch at any Thing that stands next them; and so, although such slim and feeble Plants, yet easily climb to a very great hight.
8. §. OF THE several Figures of Hairs, and their Use, B. 1. Ch. 4. I have also spoken. As to one Use, sc. the Protection they give to the Leaf, Tab. 43. I shall here further note, That the design of Nature, is the more evident if we consider, That all Leaves are not alike Hairy, nor at all times, nor in every part: but differently, according to their Age, Substance, Texture, and Foulding up. Their Age; for there are many young Buds covered with a thick warm Hair, which afterwards dries up and disappears, as useless; as those of the Vine, Golden Liverwort, &c. Their Substance; so those Buds which are tenderest, and would sooner feel the cold, if naked, have the fullest Hair; as of Thistle, Mullen, Burdock, and others. Their Structure; therefore those Leaves, whose Fibres stand more prominent or above their Surface, lest the cold should nip them, are covered with greater Store of Hair; as in Moth-Mullen, Garden-Clary, and the like. And their Fould; it being observable, That those Leaves which are folded up inward, have little or no Hair on their inner, but only on their Back-Sides, which are open to the Aer; as is visible in Corin, Warden, Golden Liverwort, and others.
9. §. Add hereto, That where there is Store of Hair, Nature is the less sollicitous for other Covers; and where there is not, she is more. So the Leaves of Beans and Peasen, of Nettle, Plantain, &c. not being Hairy, have each a Surfoyl, or else certain Hairy Thrums, to protect them. And those Plants which have neither, are such as have a Hotter Juyce, and so less subject to the impressions of Cold, as Speerwort, Scurvygrass, Watercress, Fenil, and most of the Umbelliferous Kind.
10. §. Hair is of use to preserve young Buds, not only, from the cold Aer, but also from too much Wet; which, if it were contiguous, especially in Winter, would often rot and destroy them. But being made to stand off in drops at the ends of the Hair, doth not hurt, but refresh them. Thus doth Nature make the meanest Things sometimes subserve to the best Ends.