Species Synonyms
In scientific literature and herbariums, the following Latin names are used to designate this species: Vitis arizonica Engelmann, Vitis aestivalis Wright, Vitis californica (according to the 1870 United States Department of Agriculture report), and Vitis arizonensis (according to the 1871 report). In American viticultural practice, the common name Gulch Grape, proposed by viticulturist Thomas Munson, is also documented.
Historical Background and Geographical Distribution
The Vitis arizonica species was classified and named by George Engelmann in August 1868. The first specimens of this plant were collected by Charles Wright in 1851 in New Mexico, who initially misidentified it as Vitis aestivalis. Notably, one of the specimens he collected, currently preserved in the Cambridge Herbarium, contains phylloxera galls.
This species occupies a relatively limited geographical range. It is primarily distributed in the state of Arizona, where it grows along the banks of water bodies as well as on arid elevations and hills. Wild populations have also been recorded in New Mexico (in the Santa Magdalena Mountains), Texas (Presidio and Uvalde counties), southern Utah, and Mexico—specifically in the state of Chihuahua at altitudes up to 2,400 meters above sea level, and in the vicinity of Mexico City. In the Washington herbarium collections, specimens from these regions were occasionally mislabeled as Vitis arizonensis, Vitis californica, or Vitis riparia.
Morphological Similarity and Taxonomy
The young leaves of Vitis arizonica show a clear morphological resemblance to Vitis californica. However, the adult leaves of Vitis arizonica—being glabrous, thick, and small—allow for a distinct differentiation between the two species. Due to the existence of numerous natural hybrids between them, field classification can sometimes be difficult. In terms of its bushy habit, abundant branching, and leaf appearance, Vitis arizonica shares the closest affinity with Vitis rupestris.
Agricultural Value and Technical Characteristics
This species was practically never propagated in France. In northern California, experimental trials were conducted using Vitis arizonica as a rootstock. Regarding its environmental adaptability, the species closely resembles Vitis rupestris: in relatively dry, stony soils, it develops a more robust trunk than Vitis riparia under identical conditions. However, in fertile soils, the vigor of Vitis arizonica is inferior to that of Vitis riparia.
Vitis arizonica produces fewer suckers than Vitis rupestris, roots better from cuttings, and is less resistant to grafting. In experiments conducted by Professor Hilgard, the rooting success rate of cuttings reached 97%. Initially, Californian viticulturists considered this species a promising rootstock for arid regions, but eventually abandoned it in favor of Vitis rupestris. Vitis arizonica exhibits moderate resistance to phylloxera and low resistance to lime-induced chlorosis. Today, the Vitis arizonica grape species is preserved primarily in ampelographic collections.
Botanical and Morphological Description
- Vine and Trunk: The vine possesses moderate vigor with a spreading or bushy growth habit. The trunk is sufficiently robust, and the wood is hard and greenish-white. The bark on the trunk displays a grayish-brown tint beneath the exfoliating strips; the older bark sheds in irregular, interlaced shreds of a dark gray or blackish color.
- Young Shoots and Buds: The buds are large, conical, and surrounded by long scales with sparse, white, flocculate pubescence. The young leaves open relatively late; they are light green and glossy on both sides. Fine, thread-like hairs are present on the upper surface of young leaves, while strongly prominent veins stand out distinctly on the lower surface.
- Annual Canes: The canes are long, robust, trailing, and cylindrical, with weakly defined nodes. Branching is intensive. Wood maturity occurs early. The mature annual cane features a grayish-russet coloration with rare flakes of cobwebby hairs around the nodes (which are sometimes glabrous), and the surface is glossy without a waxy coating. The furrows are wide and well-marked. In its herbaceous state, the shoot is dull green, glossy, and covered with flocculate pubescence. The internal structure of the wood is hard and yellowish-white. The pith is weakly developed, occupying no more than one-fifth of the cane's diameter. The diaphragms are plano-convex, slightly uneven, and 1 to 2 mm thick. The internodes are short. The tendrils are intermittent, thin, long, and bifid.
- Leaf: The leaves are small (length and width do not exceed 6 cm) and cordate. The leaf base is wide and rounded, the apex is obtuse, and the blade asymmetry is weakly pronounced. The leaves are entire or have three weakly developed lobes (in which case the lateral lobes are marked only by a larger terminal tooth). The petiolar sinus is V-shaped and widely open. The leaf blade is thin and parchment-like (occasionally thicker and leathery), smooth, and slightly trough-shaped with upturned margins. On the upper surface, the veins are weakly defined; the teeth are wide and obtuse, with a distinct yellowish mucro. The upper surface of the leaf blade is dark green and intensely glossy, with faint cobwebby hairs at the base of the main veins near the petiolar sinus. The lower surface is paler, lacquered or matte grayish-green, with sparse tufts of cobwebby hairs at the junctions of the secondary veins. The main veins on the lower surface are robust, strongly prominent, and exhibit a wine-red coloration at the base. The petiole is short, cylindrical, set at a right angle to the leaf blade, and grooved along its entire length.
- Inflorescences and Berries: The cluster is small, elongated, weakly branched (without pronounced lateral lobes or shoulders), and irregularly cylindrical. The peduncle is short and slender. The pedicels are short and thin, with a flat thickening (cushion) and small verrucosities. The berries are small, spherical, deep black, and feature a faint bluish pruinose bloom. The texture is firm, and the skin is thick and elastic. The pulp is melting, the juice is sparse, and the flavor is subacid.
- Seeds: The berry contains two or three seeds. The seeds are relatively large and round-compressed (5 mm long, 2.5 mm wide), dark brick-red, and matte or slightly glossy. The seed depressions (furrows) are barely visible. The beak is short and thick. The chalaza is oval, weakly prominent, and transitions into a thread-like raphe that disappears before reaching the bilobed base of the seed (pic. 698-699).
