CHAP. ij. 
LEAVES. 
109 
Tliis kind of leaf has not been before distinguished: it may 
be considered intermediate between those without veins and 
those in which primary veins are first apparent. The veins 
are equal in power to the proper veinlets of leaves of a higher 
class. 
3. Straight'Veined (rectivenium) . In this the veins are en- 
tirely primary, generally very much attenuated, and arising 
from towards the base of the midrib, with which they lie 
nearly parallel : they are connected by proper veinlets ; but 
there are no common veinlets. The leaves of Grasses and of 
Palms and Orchideous plants are of this nature. This form 
has been called by Link ^^amZ/e/z and convergenti-nervosum, 
according to the degree of parallelism of the primary veins; 
and to these two he has added what he calls venuloso-nervosum^ 
when the primary veins are connected by 'proper veinlets: 
but as this is always so, although it is not in all cases equally 
apparent, the term is superfluous. Ach. Richard calls this 
form laterinervium, and De Candolle rectinervium ; from which 
I do not find it advisable to distinguish his ruj^tinervmm^ 
which indicates the straight- veined leaf, when the veins are 
thickened and indurated, as in the Palm tribe. 
4. Curve-veined (curvivenium) . This is a particular modifi- 
cation of the last form, in which the primary veins are also 
parallel, simple, and connected by unbranched proper vein- 
lets ; do not pass from near the base to the apex of the leaf, 
but diverge from the midrib along its whole length, and lose 
themselves in the margin. This is the folium liinoideum 
and venuloso-hinoideum of Link, the f, penninervium of A. 
Richard, and the f. curvinernium of De Candolle. It is com- 
mon in Scitamineae. It is not improbable that both this and 
the last ought to be regarded as peculiar modifications of 
petiole (a kind of phyllodia), rather than as true leaves analo- 
gous to those next to be described. 
5. Netted [reticulatum). Here the whole of the veins that 
constitute a completely developed leaf are present, arranged 
as I have above described them, there being no peculiar com- 
bination of any class of veins. This is the common form of 
the leaves of Dicotyledons, as of the Lilac, the Rose, &c. It 
is the folium venosum of Linnaeus, the f. indirecte venosum 
