5 cm long, oblong in outline; petioles 10-12 mm long, winged, somewhat aromatic when crushed; rachis more narrowly winged than petiole, involute when drying, and appearing quadrangular; leaflets 7-11, 5-6 x 6-9 mm, subsessile, semi-succulent, and broadly obovate to broadly elliptic, yellowish-green, opaque, midvein
on abaxial surface prominent; indument spiculate on stems, reproductive structures glabrous, foliage with resinous papilla.
The arrangement of the vascular system in the petiole and the midvein
are useful in the diagnosis of some plant species.
2 cm, fleshy, glabrous on both surfaces, venation obscure especially on the upper surface, formed by a midvein
and two pairs of pinnate secondary veins, base decurrent, apex obtuse.
Prickly lettuce can be easily distinguished by the row of spines on the midvein
ridge of its leaves.
Eggs are laid in slits in the midvein
on the upper side of the leaves.
Each petal has a conspicuous but not prominent midvein
and several secondary veins parallel to the midvein
that dichotomize towards the margin (Fig.
The leaf midvein
was single, reddish in color and the reddish color of midvein
is one of the most important characteristics of the species under study (Fig.
8:1; apices commonly retuse, sometimes rounded; crenate-dentate; leaves when yet unfolded adaxially subglabrous, with minute glandular hairs throughout, pubescent and tomentose over teeth, and puberulent here and there on surface, pubescent from a few teeth apices, tufted on midvein
and some secondary veins, when newly unfolded adaxially subglabrate except at apex and base; abaxially pubescent (rays planar), golden-tomentellous, later glabrate, glabrescent, gray trichomes, with primary to fifth order veins raised; white striae (wax?
Leaves basal and cauline, the lowest with much reduced blades, 3-ranked; sheath present, glabrous to pubescent; blades usually well developed, linear to filiform, midvein
prominent; contra-ligule usually prolonged beyond top of sheath.
Leaflets often curled inward or twisted around the midvein
as they became necrotic and dry.
Some examples of measurable characters are blade length, petiole length, ratio of petiole length to blade length, number of teeth on the margin, angle between the midvein
and first major vein to branch off, ratio of blade length to width, angle between the first and second lobes, and total number of lobes.
Pecopteroid venation, midrib straight, prominent, with seven pairs of lateral veins that bifurcate near the midvein