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Plant Characters And Growth Habits Of The Grape








A grape plant is a complex organism with its many separate parts
especially developed to do one or a few kinds of work. The part of a
plant devoted to one or a group of functions is called an organ. The
chief organs of the plant are the root, stem, bud, flower, leaf, fruit
and seed. Flowers and leaves, it is true, develop from buds and the
seeds are parts of the fruits, but for descriptive purposes the vine
may well be divided into the parts named. These chief organs are
further divided as follows:

The root.

Root-crown: The region of the plant in which root and stem
unite.
Tap-root: The prolongation of the stem plunging vertically
downward.
Rootlets: The ultimate divisions of the root; usually of one
season's growth.
Root-tips: The extreme ends of the rootlets.

The roots of some species of the grape are soft and succulent as those
of V. vinifera, while the same organs in other species, as in most
American grapes, are hard and fibrous. They may also be few or
numerous, deep or shallow, spreading or restricted, fibrous or
non-fibrous. The structure of the root thus becomes important in
distinguishing species.

The stem.

Stem or trunk: The unbranched main axis of the plant above
ground.
Branches or arms: Main divisions of the trunk.
Head: The region from which branches arise.
Old wood: Parts of the vine older than one year.
Canes: Wood of the current season.
Spurs: Short pieces of the bases of canes; usually one or two
nodes with a bud each.
Renewal spurs: Spurs left to bear canes the following year.
Shoots: Newly developed succulent stems with their leaves.
Fruit-shoots: Flower and fruit-bearing shoots.
Wood-shoots: Shoots which bear leaves only.
Laterals: Secondary shoots arising from main shoots.
Water sprouts: Shoots arising from adventitious buds.
Suckers: Shoots arising from below ground.
Nodes: Joints in the stem from which leaves are or may be borne.
Internodes: The part between two nodes.
Diaphragm: The woody tissue which interrupts the pith at the
node.
Bloom: The powdery coating on the cane.
Tendril: The coiled, thread-like organ by which the vine grasps
an object and clings to it.

Species of grapes have very characteristic vines. A glance at a vine
enables one to tell the European grape from any of the American
grapes; so, also, one is able to distinguish most of the American
species by the aspect of the vine. Many varieties of any species of
grape are readily told by the size and habits of the plant. Size of
vine is rather more variable than other gross characters because of
the influence of environment, such as food, moisture, light, isolation
and pests; yet, size in a plant or the parts of a plant is a very
reliable character when proper allowances are made for environment.

The degree of hardiness is a very important diagnostic character in
determining both species and varieties of grapes and very largely
indicates their value for the vineyard. Thus, the varieties of the
European grape are less hardy than the peach, while our American
Labruscas and Vulpinas are as hardy as the apple. The range of
varieties as to hardiness falls within that of the species, and
cultivated varieties hardier than the wild grape are not found. Grapes
are designated in descriptions of varieties and species as hardy,
half-hardy and tender.

Habit of growth varies but little with changing conditions and is thus
an important means of distinguishing species and varieties and not
infrequently stamps the variety as fit or unfit for the vineyard.
Habit of growth gives aspect to the vine. Thus, a vine may be upright,
drooping, horizontal, stocky, straggling, spreading, dense or open.
The vine may grow rapidly or slowly and may be long-lived or
short-lived; the trunk may be short and stocky or long and slender.
These several characters largely determine whether a vine is
manageable in the vineyard. Productiveness, age of bearing and
regularity of bearing are distinctive characters with cultivated
grapes. The care given the vine influences these characters; yet all
are helpful in identifying species and varieties and all must be
considered by the grape-grower.

Immunity and susceptibility to diseases and insects are most valuable
diagnostic characters of species and varieties of grapes. Thus,
species differ widely in resistance to phylloxera, the grape-louse, to
the grape leaf-hopper, the flea-beetle, berry-moth, root-worm,
powdery-mildew, downy-mildew, anthracnose and other insect and fungous
troubles of this fruit.

The structure of the bark is an important distinguishing character for
some species, but is of little importance in identifying the variety
and has no economic value to the fruit-grower. In most species of
grapes, the bark has distinct lenticels and on the old wood separates
in long thin strips and fibers; but in two species from southeastern
North America, the bark bears prominent lenticels and never shreds.
Smoothness, color and thickness are other attributes of the bark to be
noted.

Canes of different species vary greatly in total length and in length
of internodes. They vary also in size, in number and in color, while
the shape in some species is quite distinctive, being in some round,
in others angular and in still others flattened. The direction of
growth in canes, whether sinuous, straight or zigzag, is an important
character. Nodes and internodes are indicative characters in some
species, being more or less prominent, angular or flattened, while the
internodes are long or short.

The diaphragm distinguishes several species of grapes. The cane
contains a large pith and this in most species is interrupted by woody
tissue, forming a diaphragm at the nodes. In the Rotundifolia grapes
the diaphragm is absent, while in several other American species it is
very thin and in still others quite thick. The character of the
diaphragm is best observed in year-old canes. In studying the
diaphragm, notice should be taken also of the pith, which is very
variable in size.

Young shoots of the grape offer a ready means of distinguishing
species and varieties through their color and the amount and
character of the pubescence. Shoots may be glabrous, pubescent or
hairy and even spiny.

The tendril is one of the organs most used in determining species and
varieties of grapes. In some species, as V. Labrusca, there is a
tendril or an inflorescence opposite nearly every leaf, continuous
tendrils. All other species have two leaves with a tendril opposite
each and a third leaf without a tendril, intermittent tendrils. To
study this organ it is necessary to have vigorous, healthy, typical
canes. Tendrils may be long or short, stout or slender; simple,
bifurcated or trifurcated; or smooth, pubescent or warty.

The number of inflorescences borne by species is an important
character in some cases. All species, excepting V. Labrusca, average
two inflorescences to a cane, but V. Labrusca may bear from three to
six inflorescences, each in the place of a tendril opposite the leaf.

The bud.

Bud: An undeveloped shoot.
Fruit-bud: A bud in which a shoot bearing flowers originates.
Wood-bud: A bud in which a shoot bearing only leaves originates.
Latent bud: A bud which remains dormant for one or more seasons.
Adventitious bud: A bud arising elsewhere than the normal
position at a node.
Eye: A compound bud.
Main bud: The central bud of an eye.
Secondary bud: The lateral bud of an eye.

Buds of different species of grapes vary greatly in time of opening as
they do somewhat in varieties, so that the time the buds begin to
swell is a fine mark of distinction. The angle at which the bud stands
out from the branch is of some value in determining species.
Differences in color, size, shape, position and amount of pubescence
of buds must all be noted in describing grapes. The scales of the buds
vary more or less in size and in thickness.

The flower.

Staminate: Having stamens and not pistils; a male flower.
Pistillate: Having pistils and not stamens; a female flower.
Dioecious: Said when the stamens are on one plant and the
pistils on another.
Polygamous: Said when flowers on a plant are in part perfect
(having both stamens and pistils) while others are
staminate or pistillate.
Hermaphrodite: Said of a flower having both stamens and pistils.
Fertile: Said of a flower capable of bearing seed without pollen
from another flower.
Sterile: Said of a flower without or with abortive pistils.
Perfect: Said of a flower having both stamens and pistils.
Imperfect: Said of a flower wanting either stamens or pistils.
Peduncle: The stalk of a flower-cluster.
Pedicel: The stalk of each particular flower.

The time of bloom is an easy mark of distinction between several
species of grapes and helps to distinguish varieties in a species as
well. Most species of grapes bear fertile flowers on one vine and
sterile flowers on another and are, therefore, polygamous-dioecious.
Sterile vines bear male flowers with abortive pistils so that, while
they never produce fruits themselves, they usually assist in
fertilizing others. Fertile flowers are capable of ripening fruits
without cross-pollination. Vines with female flowers only are seldom
found. In most species of the grape, plants with sterile flowers and
those with complete flowers are found mixed in the wild state, but
usually only the fertile plants have been selected for cultivation.
Plants raised from seeds of any of the species, however, furnish many
sterile vines.


The degree of fertility of blossoms is also a fine mark of distinction
in species and varieties of the grape. Fertile vines are of two kinds
in most species. The flowers on one kind are perfect hermaphrodites,
while in the other kind the stamens are smaller and shorter than the
pistil and eventually bent down and curved under. The two kinds of
stamens are shown in Figs. 53 and 54. These may be called imperfect
hermaphrodites since they are seldom as fruitful as the perfect
hermaphrodites unless fertilized from another plant. Examined with a
microscope, it is found that self-sterile plants usually bear abortive
pollen and that the percentage of abortive pollen grains varies
greatly in different varieties. The upright or depressed stamen does
not always indicate the condition of the pollen, since there are many
instances in which upright stamens bear impotent pollen and
occasionally the depressed stamens bear perfect pollen.


Delaware; right, depressed stamens of Brighton.]

The leaf.

Blade: The expanded portion of the leaf.
Lobe: The more or less rounded division of the leaf.
Sinus: The recess or bay between two lobes.
Petiole: The leaf-stalk.
Petiolar sinus: The sinus about the petiole.
Basal sinuses: The two sinuses toward the base of the blade.
Lateral sinuses: The two sinuses toward the apex of the blade.

The size, shape and color of the leaves are quite distinctive of
species and more or less so of varieties, if allowances are made for
variation due to environment. The lobing of leaves is a very uniform
character in most species, some having lobes and others having entire
leaves. The upper surface of the leaf in some species is smooth,
glossy and shiny and in others is rough and dull. The lower surface
shows similar variations and has, besides, varying amounts of
pubescence, down and bloom. In some species the down resembles
cobwebs. The number, size and shape of the lobes are important in
distinguishing both varieties and species, as are also the petiolar,
basal and lateral sinuses. As in most plants, the margins of the
leaves, whether serrate, dentate or crenate, are often distinguishing
characters. The petiole in different species varies from short to long
and from stout to slender. Lastly, the time at which the leaves fall
is often a good distinguishing mark.

The fruit.

Peduncle and pedicel: Defined as in flower.
Brush: The end of the pedicel projecting into the fruit.
Base: The point of attachment of bunch or berry.
Apex: The point opposite the base.
Bloom: The powdery coating on the fruit.
Pigment: The coloring matter in the skin.
Quality: The combination of characters that makes grapes
pleasant to the palate, sight, smell and touch.
Foxiness: The rancid taste and smell of some grapes which are
similar to the effluvium of a fox.

Of all organs the fruit is most responsive to changed conditions and
hence most variable. Yet the fruits furnish most valuable characters
for determining both species and varieties. Size, shape, compactness
and the number of clusters on a shoot must be noted. Coming to the
berry, size, shape, color, bloom, adherence of stigma to the apex and
adhesion of fruit to the pedicel are all of value. Difference in
adherence of the skin to the pulp separates European from all American
grapes. The thickness, toughness, flavor and pigment of the skin have
more or less value. The color, firmness, juiciness, aroma and flavor
of the flesh, as well as its adherence to seed and skin, are valuable
marks in describing grapes. All species and varieties are well
distinguished by the time of ripening and by keeping quality. The
color of the juice is a plain and certain dividing line between some
species and many varieties.

The seed.

Beak: The narrow prolonged base of the seed.
Hilum: The scar left where the seed was attached to the
seed-stalk.
Chalaza: The place where the seed-coats and kernel are
connected.
Raphe: The line or ridge which runs from the hilum to the
chalaza.

Seeds are accounted of much value in determining species. The size and
weight of seed differ greatly in different species, as they do also in
varieties of any one species. Thus, of native grapes, Labrusca has the
largest and heaviest seeds and Vulpina has the smallest seed, while
those of AEstivalis are of medium size and weight. The shape and color
of seed offer distinguishing marks, while the size, shape and position
of the raphe and chalaza furnish very certain marks of distinction in
some species.





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Previous: Grape Botany



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