Sargent, Charles S. 1889. Vaccinium hirsutum. Gard. & Forest. 2: 364, 365, fig. 119.
Ericaceae
Species Description - Plants often in fairly large colonies, 30-80 cm. (sometimes 1 m.) high. Leaves deciduous, veiny and appearing subcoriaceous, usually pale green to subglaucous; the lower surface non-glandular, glabrous or sometimes pubescent along the veins; elliptic, sometimes ovate-elliptic and acuminate, 1.5-2.5 cm. wide, 3-5 cm. long; the margin serrate. Corolla cylindraceous to cylindro-campanulate, 4-5(6) mm. long, greenish-white, or often tinged with pink. Fruit dark blue, or even black, or sometimes quite glaucous, 5-7 mm. in diam., usually of only fair quality.
V. viride Ashe, Torreya 25: 11. 1925. Not V. pallidutm of various authors.
Diploid (2n = 24).
Throughout much of the Southern Appalachian Mts., one finds a tetraploid species, V. simulatum, which has fairly constant characters modified only in those areas where it has hybridized with other species. Therefore, except for these known hybrid forms, V. simulatium is reasonably stable, having the type of homogeneous population one learns to associate with autopolyploid species. Working backward from this basi'c element of the apparently autopolyploid V. simulatum, one might arrive at a reasonably accurate concept of the ancestral diploid, even to a prediction of the probable size of its parts and something of its ecological preferences. Having done this, it would remain only to ascertain if such a plant exists. It does-and in considerable abundance-and is t-he material herein delimited as Vaccinium pallidum, a -plant we have known for years but had refused to think of as anything more than a peculiarly coarse and aberrant form of V. vacillans.
It is admittedly difficult to know just where to draw the line between the upland pallidtm and the lowland vacillans, for they have hybridized in the past and the segregate forms today fill the gap, both morphologically aud distribu- tionally, between the two basic populations (fig. 9). There is considerable evidence that these two were ecologically and geographically disjunct until the Pleistocene, at which time the upland species probably was forced to lower levels where it came into contact with the lowland species (see also the discussion of this same topic under V. vacillans). However, there is no intention of intimating here that these two mutually engulfed each other by hybridization to form a common (mictonic) community; rather, only their margins made contact, for at the end of the Pleistocene (and this is especially true along the eastern scarp of the Blue Ridge), pallidumt apparently returned to its old homue, but little changed except for having picked up some extra glauceseence. This last statement is by no means fanciful, but' is based on examinations of local populations of pallidum growing on various ranges west of the Blue Ridge in areas where vacillans is sometimes rare, or even absent; there, V. pallidum is searcely if at all glaucous, and the fruit may even be quite dark. It should also be noted here that. the western (viride) phase of pallidum usually has shining black fruit. Furthermore, it is quite unlikely that there would be any confusion over the delimitation of these two were it not for the fact that clearing operations since the advent of the Colonial settlers have opened up vast areas where certain elements of both species have again met and continued the process begun in the Pleistocene. But in spite of the presence of many confusing individuals, a considerable amount of reasonably pure material of both paltiddum and vacillans still exists. In fact, some nearly pure V. pallidutm is now to be found at various places on the Pied- mont, very near the coastal plain.
If these two were the only entities involved, there perhaps would be some reason for considering them as subspecies under a single binomial; but, even then, the problem of distinguishing them would be no less than if treated as species. In addition, the apparently aberrant characters of vacillans, which at first glanee may appear to have been derived fromu pallidum, may prove otherwise when care- fully examined. For example: as will be demonstrated later under that species, the original form of V. vacillaqns was a low-growing plant with small, entire leaves, and is still this type in many areas. Taller plants with coarser leaves itesult from crossing with pallidum, but vacillans also hybridizes with various of the high- bush, larger-leafed diploids; also, the hybrids with pallidum have serrate leaves which, while longer, tend to be relatively narrower than is typical for vacillans, but vacillans has also hybridized freely with the serrate and narrow-leafed angus- tifolium. Hence, any attempt to draw a morphologically median line between pallidum and vacillans based on the usual criteria would lead to a greater con- fusion than now exists. Because of the foregoing, it has lately become my policy to interpret V. pallidum with a certain degree of precision, permitting the questionable material to fall into V. vacillans. Since vacillans already held so many variant forms derived from a variety of sources, it appeared that the addition of a few more could do but little injury to the specific concept of this already polymorphic aggregation.
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