110 
ORGANOGRAPHY. 
BOOK I. 
of Link, tlie f. mixtinervium of A. Richard, and the /I retiner- 
vium of De Candolle. If the external veins and marginal 
veinlets are conspicuous, Link calls this form comhinate veno- 
sum ; but if they are indistinct, he calls it evanescent^ 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. ha- 
sinervia, and De Candolle f, triplinervia and f. 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 margin, as in all Myr- 
taceae. 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 f. directe venosum 
of Link : it is the f. digitinervium of A. Richard. Hither I 
refer, without distinguishing them, the f, pedalinervia^ palmi- 
nervia, aj\d peltinervia 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 venae primariae 
of a reticulated leaf pass in a right line from the midrib to the 
margin, as in Castanea. This has the same relation to the 
