Botany of the Tomato

The common tomato of our gardens belongs to the natural order Solanaccae and

the genus Lycopcrsiciun. The name from lykos, a wolf, and persica, a peach, is

given it because of the supposed aphrodisiacal qualities, and the beauty of the

fruit. The genus comprises a few species of South American annual or short-

lived perennial, herbaceous, ranksmelling plants in which the many branches are

spreading, procumbent, or feebly ascendent and commonly 2 to 6 feet in length,

though under some conditions, particularly in the South and in California, they

grow much longer. They are covered with resinous viscid secretions and are

round, soft, brittle and hairy, when young, but become furrowed, angular, hard

and almost woody with enlarged joints, when old. The leaves are irregularly

alternate, 5 to 15 inches long, petioled, odd pinnate, with seven to nine short-

stemmed leaflets, often with much smaller and stemless ones -between them.

The larger leaflets are sometimes entire, but more generally notched, cut, or

even divided, particularly at the base. The flowers are pendant and borne in

more or less branched clusters, located on the stem on the opposite side and

usually a little below the leaves ; the first cluster on the sixth to twelfth

internode from the ground, with one on each second to sixth succeeding one.

The flowers (Fig. 2) are small, consisting of a yellow, deeply five-cleft, wheel-

shaped corolla, with a very short tube and broadly lanceolate, recurving petals.

Fig. 2 Tomato Flowers Enlarged about 2 l/2 Times. Section
of Flower Shown at Right
(Drawn from a photograph by courtesy of Prof. L. C. Corbett)

The calyx consists of five long linear or lanceo-late sepals, which are shorter than

the petals at first, but are persistent, and increase in size as the fruits mature.

The stamens, five in number, are borne on the throat of the corolla, and consist

of long, large anthers, borne on short filaments, loosely joined into a tube and

opening by a longitudinal slit on the inside, and this is the chief botanical

distinction between this genus and Solatium to which the potato, pepper, night

shade and tobacco belong. The anthers in the latter genus open at the tip only.

The two genera, however, are closely related and plants belonging to them are

readily united by grafting. The Physalis, Husk tomato or Ground cherry is quite

distinct, botanically.

Fig. 3 Two-Celled Tomato, Fig. 4 Three-Celled Tomato

The pistils of the true tomato are short at first, but the style elongates so as to

push the capitate stigmathrough the tube formed by the anthers, this usually

occurring before the anthers open for the discharge of the pollen. The fruit is a

two to many-celled berry with central fleshy placenta and many small

kidney shaped seeds which are densely covered with short, stiff hairs, as seen in

Figs. 3 and 4. It is comparatively easy to define the genus with which the

tomato should be classed botanically, but it is by no means so easy to classify

our cultivated varieties into botanical species. We have in cultivation varieties

which are known to have originated in gardens and from the same parentage,

but which differ from each other so much in habit of growth, character of leaf

and fruit and other respects, that if they had been found growing wild they would

unhesitatingly be pronounced different species, and botanists are not agreed as

to how our many and very different garden varieties should be classified

botanically. Some contend that all of our cultivated sorts are varieties of but two

distinct species, while others think they have originated from several.

Classification– The author suggests the following classification, differing

somewhat from that sometimes given, as he believes that the large, deep-

sutured fruit of our cultivated varieties and the distinct pear-shaped sorts come

from original species rather than from variations of Lycopersicum cerasiforme:

Currant tomato, Grape tomato, German or Raisin tomato (Lycopersicum

pimpinellifolium, L. racemiforme) (Fig. 5). Universally regarded as a distinct

species. Plant strong, growing with many long, slender, weak branches which are

not so hairy, viscid,* or ill-smelling, and never become so hard or woody as

those of the other species. The numerous leaves are very bright green in color,

leaflets small, nearly entire, with many small stemless ones between the others.

Fruit produced continuously and in great quantity on long racemes like those of

the currant, though they are often branched. They continue to elongate and

blossom until the fruit at the upper end is fully ripened. Fruit small, less than 1/2

inch in diameter, spherical, smooth and of a particularly bright, beautiful red

color which contrasts well with the bright green leaves, and this abundance of

beautifully colored and grace fully poised fruit makes the plant worthy of more

general cultivation as an ornament, though the fruit is of little value for culinary

use. This species, when pure, has not varied under cultivation, but it readily

crosses with other species and with our garden varieties, and many of these owe

their bright red color to the influence of crosses with the above species.

Fig. 5 Currant Tomato and Characteristic Clusters
Cherry tomato

(L. ccrasiforme) (Fig. 6). Plant vigorous, with stout branches

which are distinctly trailing in habit. Leaves flat or but slightly curled. Fruit

Fig. 6 Red Cherry Tomato

very abundant, borne in short, branched clusters, globular, perfectly smooth, with

no apparent sutures. From 1/2 to 3/4 inch in diameter and either red or yellow in

color, two-celled with numerous comparatively small, kidney-shaped seeds. Many

of our garden varieties show evidence of crosses with this species, and by many

it is regarded as the original wild form of all of our cultivated sorts. These, when

they escape from cultivation and become wild plants, as they often do, from New

Jersey southward, produce fruit which, in many respects, resembles that of this

species in size and form ; but they are generally more flattened, globeshaped,

with more or less distinct sutures on the upper side, and I have never seen any

fruit of these wild plants which could not be readily distinguished from that of the

true Cherry tomato. Prof. P. H. Rolfs, Director of the Florida experiment station,

reports that among the millions of volunteer, or wild, tomatoes he has seen

growing in the abandoned tomato fields in Florida, he has never seen a plant

with fruit which could not be easily distinguished from that of the true Cherry

tomato. Again, one can, by selection and cultivation, easiy develop from these

wild forms plants producing fruit as large and often practically identical with, that

of our cultivated varieties, while I have given a true stock of Cherry tomato most

careful cultivation on the best of soil for 20 consecutive generations without any

increase in size or change in character of the fruit.

Pear (not Plum) tomato (L. pyriforme) (Fig. 7).

Plant exceptionally vigorous, with comparatively few long, stout stems inclined to

ascend. Leaves numerous, broad, flat, with a distinct bluish-green color

noticeable, even in the cotyledons. Fruit abundant, borne in short branched or

straight clusters of five to ten fruits. It is perfectly smooth, without sutures, and

of the shape of a long, slender-necked pear, not over an inch in transverse by

1 1/2 inches in longitudinal diameter. When the stock is pure the fruit retains this

form very persistently. The production of egg-shaped or other

Fig. 7 Pear-Shaped Tomato

forms is a sure indication of impure stock. They are bright red, dark yellow, or

light yellowish white in color, two-celled, with very distinct central placenta

and comparatively few and large seeds. The fruit is inclined to ripen unevenly, the

neck remaining green when the rest of the fruit is quite ripe. It is less juicy

than that of most of our garden sorts but of a mild and pleasant flavor. This is

Fig. 8 Yellow Plum Tomato, Showing Most Usual Form of Cluster

considered, by many, to be simply a garden variety, but I am inclined to the

belief that it is a distinct species and that the contrary view comes from the

study of the impure and crossed stocks resulting from crosses between the true

Pear tomato and garden sorts which are frequently sold by seedsmen as pear-

shaped. Many garden sorts like the Plum (Fig. 8), the Egg, the Golden Nugget,

Vick’s Criterion, etc. are known to have originated from crosses of the Pear and I

think that most, if not all, the garden sorts in which the longitudinal diameter of

the fruit is greater than its transverse diameter owe this form to crosses with L.

pyriforme.

Cultivated varieties (L. esculentum). This is commonly used as the botanical

name of our cultivated varieties, rather than as the name of a distinct species.

In western South America, however, there is found growing a wild plant of

Lycopersicum which differs from the other recognized species in being more

compact in growth, with fewer branches and larger leaves, and carrying an

immense burden of fruit borne in large clusters. The fruit is larger than that of

the other species but much smaller than that of our cultivated sorts; is very

irregular in shape, always with distinct sutures, and often deeply corrugated and

bright red in color. The walls are thin ; the flesh is soft, with a distinct sharp, acid

flavor much less agreeable than that of our cultivated forms of garden tomatoes.

This has commonly been regarded by botanists as a degenerate form of our

garden tomatoes, rather than as an original species, but I find that, like L.

cerasiforme and L. pyriforme, it is quite fixed under cultivation, except as

crossed with other species or with our garden varieties, and I believe it to be the

original species from which our cultured sorts have been developed, by crossing

and selection.

Fig. 9 One of the First Illustrations of the Tomato
Poma amoris, (Pomum aureum), (Lycopersicum), 1581

Such crosses probably were made either naturally or by natives before the

tomato was discovered by Europeans. The earliest prints we have of the tomato

(Figs. 9 and 10) are far more like the fruit of this plant than that of L.

cerasiforme, and the prints of many of the earliest garden varieties and of some

sorts which are still cultivated in southern Europe, for use in soups, are like it not

only in size and form, but in flavor. These facts make it seem far more probable

that our cultivated sorts have come, by crossing, between this and other species

rather than by simple development from L. cerasiforme. Prof. E. S. Goff, of

Wisconsin, who has made a most careful study of the tomato, expressed the

Fig. IO An Early Illustration of the Tomato
(From Morrison’s “Historia Universalis,” 1680)

same opinion, writing that it seemed to him that our cultivated sorts must have

come from the crossing of a small, round, smooth, sutureless type, with a larger,

deep-sutured, corrugated fruit, like that of the Mammoth Chihuahua, but smaller.

However this may be, I think that it is wise to throw all of our cultivated

garden sorts, except the Pear, the Cherry, and the Grape which I regard as

distinct species together under the name of L. esculentum, even when we know

they have originated by direct crosses with the other species ; and it is well to

classify the upright growing sorts under the varietal names, L. validum, and the

larger, heavier sorts, as L. grandifolium, as has been done by Bailey. (Cyclopedia

of Horticulture.)

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