Typical mosaic pattern on flue-cured tobacco leaves systematically infected with Tobacco mosaic virus.
Photograph courtesy H. D. Shew,
from the Compendium of Tobacco Diseases
The Plant bears from eight to twenty leaves according to the species of the plant. They have various forms, ovate, lanceolate, and pointed. Leaves
of a lanceolate form are the largest, and the shape of those found on most varieties of the American plant. The color of the leaves when growing,
as well as after curing and sweating, varies, and is frequently caused by the condition of the soil. The color while growing may be either a light
or dark green, which changes to a yellowish cast as the plant matures and ripens.
The ground leaves are of a lighter color and ripen earlier than the rest--sometimes turning yellow, and during damp weather rotting and dropping
from the stalk. Some varieties of the plant, like Latakia, bear small but thick leaves, which after cutting are very thin and fine in texture;
while others, like Connecticut seed leaf and Havana, bear leaves of a
medium thickness, which are also fine and silky after curing. But while the color of the plant when growing is either a light or dark green, it
rapidly changes during curing, and especially after passing through the sweat, changing to a light or dark cinnamon like Connecticut seed leaf,
black like Holland and Perique tobacco, bright yellow of the finest shade of Virginia and Carolina leaf, brown like Sumatra, or dark red like that
known by the name of "Boshibaghli," grown in Asia Minor.
The leaves are covered with glandular hairs
containing a glutinous substance of an unpleasant odor, which characterizes all varieties as well as nearly all parts of the plant.
The leaves of all varieties of tobacco grow the entire length of the stem and clasp the stalk, excepting those ofSyrian, which are attached by a
long stem. The size of the leaves, as well as the entire plant, is now muchlarger than when first discovered. One of the early voyagers describes
the plant as short and bearing leaves ofabout the size and shape of the walnut. In many varieties the leaves grow in a semi-circular form while
inothers they grow almost straight and still others growing erect presenting a singular appearance.
The stem or mid-rib running through the leaf is large and fibrous and its numerous smaller veins proportionally larger which on curing become
smaller and particularly in those kinds best adapted for cigar wrappers.
The leaves from the base to the center of the plant are of about equal size but are smaller as they reach the summit, but after topping attain
about the same size as the others. The color of the leaf after curing may be determined by the color of the leaf while growing--if dark green
while maturing in the field, the color will be dark after curing and sweating and the reverse if of a lighter shade of green.
If the soil be dark the color of the leaf will be darker than if grown upon a light loam. Some varieties of the plant have leaves of a smooth
glossy appearance while others are rough and the surface uneven--more like a cabbage leaf, a peculiar feature of the tobacco of Syria. The kind of
fertilizers applied to the soil also in a measure as well as the soil itself has much to do with the texture or body of the leaf and should be
duly considered by all growers of the plant.
A light moist loam should be chosen for the tobacco field if a leaf of
light color and texture is desired while if a dark leaf is preferred the soil chosen should be a moist heavy loam.