1 1 ORGANOGRAPHY. BOOK I. 



of Link, the f. mixtinervium of A. Richard, and ihef. retiner- 

 vium of De Candolle. If the external veins and marginal 

 veinlets are conspicuous, Link calls this form comhinati veno- 

 sum ; but if they are indistinct, he calls it evanescenti venosum. 



6. Ribbed {costatum). In this three or more midribs proceed 

 from the base to the apex of the leaf, and are connected by 

 branching primary veins of the form and magnitude of proper 

 veinlets, as in Melastoma. This must not be confounded 

 with the straight-veined leaf, from which it may in all cases 

 of doubt be distinguished by the ramified veins that connect 

 the ribs. This is a very material difference, which has never 

 been properly explained. Linnaeus and his followers con- 

 found the two forms; but modern writers separate them: 

 although it must be confessed that it is difficult to discover 

 their distinctions from the characters hitherto assigned to 

 them. Link calls these leaves f. nervata, A. Richard f. ba~ 

 sinervia, and De Candolle y^ trij^linervia andyi quintuplinervia. 

 If a ribbed leaf has three ribs springing from the base, it is 

 said to be three-ribbed {tri-costatum, trinerve of authors) ; if 

 five. Jive-ribbed, and so on. But if the ribs do not proceed 

 exactly from the base, but from a little above it, the leaf is 

 then said to be triply-ribbed [triplicostatum), as in the He- 

 lianthus. 



7. Falsely ribbed [pseudocostatum), is when the curved and 

 external veins, both or either, in a reticulated leaf, become 

 confluent into a line parallel with the mai'gin, as in all Myr- 

 tacece. This has not been before distinguished. 



8. Radiating [radiatum), when several ribs radiate from 

 the base of a reticulated leaf to its circumference, as in lobed 

 leaves. This and the following form the J", directe venosum 

 of Link : it is the Jl digitinervium of A. Richard. Hither I 

 refer, without distinguishing them, the f. pedalinervia, palmi- 

 nervia, and peltiyiervia of De Candolle ; the differences of which 

 do not arise out of any peculiarity in the venation, but from 

 the particular form of the leaves themselves. 



9. Feather-veined [pennivenium), when the venag primariae 

 of a reticulated leaf pass in a right line from the midrib to the 

 mai'gin, as in Castanea. This has the same relation to the 



