DATE Varieties at All Growth Stages Shown by Vegetative Characters

The introduction of date culture into the United States has involved the importation of off-shoots of many Old World varieties of the date palm and the growing of numerous seedlings in this country, some few of which are proving to be worth retaining and propagating as fruit-bearing varieties. Positive identification of these varieties is of vital importance for the development of the industry and for the protection of purchasers of offshoots, especially of rare varieties that command fancy prices. Identification by the fruit characters is the most obvious method and one as old as the industry itself. Yet confusion of varieties bearing a close resemblance in size, form, color of fruit, texture, and flavor is a frequent embarrassment to the American date grower.

Field study of details of the fruiting organs, of the size and length of the fruiting stalk, length of the fruiting head, and of the strands or shamruk, furnishes additional means of distinction which the gathered fruit does not afford. Add to the fruit characters those of the palms bearing the fruit, and we have means of positive identification of date varieties never before available. Features to be observed are the appearance of the trunk, the breadth and thickness of the leaf bases, the comparative length and stiffness or flexibility of the leaves, along with the broad outlines of the top, and its mass color, from a blue-gray on one to a yellow-green on another. The details of the foliage should be observed next. Is the rachis or midrib stout and rigid, maintaining much of this character clear to the tip? Or with a broad, thick petiole, does the rib taper to a slender apex, giving the long sweeping curve, with strength and grace combined, which characterizes the famous Menakher date of Tunis, one of the rarest of the varieties now growing in America? In sharp contrast is the Hayany variety of Egypt, with slender trunk, narrow leaf bases, slender and feathery rachis, and long, pendulous pinnæ.

Studying the leaf in greater detail, the tubular sheath of finer or coarser fiber is noted, then the spine area, longer or shorter, where the suppressed basal pinn appear as belligerent protective spines, stout and acute or slender, but sharp as needles. The spines change abruptly to pinnæ widely spaced or closely set on the rachis, which if long are usually slender and weak; if shorter, often broad, stiff, and acute.

In attachment to the rachis the folded pinnæ may turn the channel directly inward (introrse), toward the top (antrorse), or toward the base (retrorse). There is a definite grouping of these three pinnæ classes. The simplest and most frequent group is the double group, with an antrorse pinna below and a retrorse above. Triple groups have an introrse pinna between the antrorse and the retrorse, and the unusual quadruple groups have two inserted introrse pinnæ.  All three groups are regarded as normal, and the proportion of each in all the pinnæ on the leaf is highly characteristic of the different varieties of the date palm.

The size of the angles at which the different classes of pinnæ are attached to the blade is another important character and gives a very distinct aspect to the leaves of different varieties. If most of the pinnæ of a leaf are set at from 60° to 90° from the axis of the leaf and lie nearly in the plane of the blade, this is the broad, smooth, 2-ranked blade. Some varieties with strongly diverse angles show rough, ragged blades and formidable spines.

In final analysis, each date variety may be distinguished from its fellows with reasonable certainty by its vegetative characters independently of its fruits.