Sargent, Charles S. 1889. Vaccinium hirsutum. Gard. & Forest. 2: 364, 365, fig. 119.
Ericaceae
Species Description - Plants in small to extensive colonies, 15-40(50) cm. high. Leaves deciduous, usually subglaucous or sometimes merely pale; the lower surface non-glandular,, glabrous, or with a sparse, or even dense pubescence; often elliptic, either nar- rowly or broadly so, but sometimes ovate, lanceolate, oblanceolate, or even spatu- late, usually apically obtuse, but often acute, sometimes subacuminate (the first several leaves, or sometimes all the leaves, suborbicular and apically rounded), 1.5-2 cm. wide, 2-3.5 cm. long; the margin entire or serrate. Corolla variable, usually cylindro-urceolate to narrowly campanulate, 4-6 mm. long, white or greenish-white, often red-tinged and sometimes quite brick-red in bud. Fruit glaucous to dull, or even black, 5-8 mm. in diam., sometimes of fair flavor.
V. vacillans var. crinitum Fernald, Rhodora 13: 236. 1911.
V. vacillans var. columbianuqm Ashe, Rhodora 33: 195. 1931.
V. vacillans var. columbianum f. mollifolium Ashe, Rhodora 33: 195. 1931.
V. torreyanumn Camp, Am. Midl. Nat. 23: 177. 1940.
Cyanococcus vacillans Rydb. Brittonia 1: 94. 1931.
Also related and in part synonymous:
V. vacillans var. missouriense Ashe, Torreya 25: 10. 1925.
V. missouriense Ashe, Rhodora 33: 193. 1931.
V. margarettae Ashe, Torreya 18: 71. 1918.
Cyanococcus margarettae Small, Man. SE. Flora 1015, 1507. 1933.
Diploid (2n =24).
Like various of the low-growing species, V. vacillans readily regenerates after fire. This is shown by figures 14-17. These figures also indicate that the height to which the plants grow is genetically controlled and that but little height is added in successive years.
Confronted with the variability of this species, it would seem that little could be done to bring it into any systematized order. The first problem is to determine the appearance and constitution of the basic elemnent of the complex. There are two ways to do this: one is to hypothetically extract from the plants of the complex those characters which seem to be aberrancies caused by hybridizationthe residuum is the basic element of V. vacillatns prior to the gene exchanges; the other is to search for possible autopolyploid derivatives and (as in the case of simulatum and pallidtum) project back to the basic diploid. Both methods have been applied to this population; the resulting descriptions are surprisingly similar and match a plant found throughout almost the entire range of the complex, in some areas being the dominant or exclusive form, in others sometimes rare or locally absent. The description of this basic element of the complex is as follows:
VACCINIUM VACILLANS Torrey (in part); = V. torreyanum Camp.
Plants in dense colonies, often several meters in diameter, 15-35 cm. high. (Twigs pale green.) Leaves fairly glaucous, the lower surface non-glandular and glabrous, the lower leaves often suborbicular, the upper broadly elliptic, apically obtuse, 1.5-2 cm. wide, 2-2.5(3) cm. long, the margin entire and slightly revolute when mature. (Two variant leaf-forms exist: south and east of the Blue Ridge, the leaves are more narrowly elliptic and apically subacute, the extreme phase being narrowly ovate-lanceolate; in the Cumberland Mts., the leaves are inclined to be somewhat broadly ovate and occasionally with rounded bases.) Corolla 4-5 mm. long, greenish-white tinged with red. Fruit glaucous, 5-8 mm. in diameter. (See figures 18, 19.)
It has been my experience that by using this description of the basic materialone might say eu-vacitllans-the majority of departures from it could be traced to gene-exchange with some other diploid species. One of the notable exceptions is the presence in parts of the Southern Appalachians of plants with leaves which are subspatulate and often with long cuneate bases. This may be the result of some peculiar rearrangement in tissues following hybridization with the coarseleafed V. pallidum (similar plants are also found in the Ozark Plateau where the viride phase of pallidum makes contact with plants related to vacillans), or it may be an indication of the former presence of a diploid species which has become extinct, but which has left behind it residual genes in the population of vacillans. Perhaps it was genetically engulfed by vacillans and "swamped out of existence" through excessive hybridization. Somewhat similar plants also are the result of vacillans x teneUllum, but the material referred to above does not seem to be of this combination.
Since V. vacillans comes onto the coastal plain, the resulting caesariense x vacillans combinations may be a little confusing to the collector the first time they are encountered, but careful attention to the characters of the parental types will suffice to explain the various kinds of segregate offspring, many of which-naturally-are somewhat coarser than the typical vacillans. An excellent concept of such a population from the region of the Great Falls of the Potomae River, consisting of F1 individuals, segregates, and back-crosses, may be obtained mnerely by reading the original description of TVaccinium serumt Ashe (Rhodora 33: 194. 1931). The crinitum phase of vacillans is known to be reasonablv common in this region, accounting for the presence of a few forms with some pubescence. Selection of ecologically successful segregate biotypes has been active in this population (e.g., on the rocky bars and on the adjacent slopes).
Although the highbush diploid, V. atrococcum, is usually a plant of swamps hybridize with vacillans under various conditions and in many places (figs. 20-22). The character of a segregative population derived from this combina,tion has recently been discussed in some detail and need not be repeated (Camp & Gilly 1943, p. 360-363). Among the segregate forms are those which are relatively low-growing, with considerable pubescence on the leaves and with dark or black berries. Such plants were described as V. margarettae Ashe. Other collections from the region of Tallulah Falls, Rabun Co., Georgia (where Ashe got some of the material on which his concept was based) indicate the presence of apparently nearly pure V. atrococcum; and the vacillans population of the surrounding region has the scattered pubeseence characteristic of the back-crosses with the basic torreyanum phase of vacillans. Segregation and/or back-crossing of this same combination results in the material referable to V. vacillans var. crinitum Fernald, based on material from Vermont. The material called V. missouriense Ashe is slightly harder to place. It seems to be fairly close to certain of the dark-fruited margarettae-like segregates, but some of the leaves are occasionallv oblanceolate (this was noted in a previous paragraph under V. pallidutm). However, for the present, such material is included .in the vacillans-complex, for no adequate line can be found to- separate missouriense and missouriense-like plants from those of the crinitum phase, which is also found in the western portion of the range of V. vaccillans. If the characters of the possible ancestral forms are kept clearly in mind, these combinations and others, such as vacillans x tenellumt, vacillans x elliottii, and vacillans x myrtilloides, will cause but little trouble in interpretation.
As has been noted under the discussion of angustifolium, the hybrids between angustifolium and vacillans are quite common. And since it appears that in many areas today vacillans is taking over the habitat where angustifolium was once fairly abundant, the exchange of genes is more marked in the vacillans population than in that of angustifoltium. For example: Under conditions of repeated burning, angustifolium is able to hold its own in. competition with vacillans, but on certain of the gravelly hills on Long Island, N. Y., where the brush fires have been brought under control, and where angustifolium apparently was once quite common, it is unable to meet the competition pressure of vacillans and is slowly being eliminated. Yet in these areas are many plants which have a dwarfish, "twiggy" habit, a narrowly elliptic and serrate leaf, much as angustifolium, yet the leaves have the dull yellow-green color of those of vacillans. Where the two are found together, all types of intermediates may be noted. In some areas, angustifoliutm apparently has completely disappeared, yet its former presence may be deduced by the marked "angustifolioid" plants in the vacillans population. Iia the mid-Appalachian uplands the same s6quence of events may be noted. Vaccinium dobbinii Burnham47 apparently was described from plants which were fairly intermediate in character between vacillans and angustifolium.
On some occasions, similar, but coarser, plants have been noted where the hybrids are abundant; these may yet be found to be allopolyploids. It is not yet known whether V. dobbinii was described from the diploid hybrids or from the suspected polyploids; the type collection seems to match the coarser material. A plant growing at the Arnold Arboretum and labeled "Vaccinium dobbinii" has been found to be tetraploid.
It will be obvious that no attention has been given to the problem of subspecific nomenclature in V. vacillans, nor is it my intention to do so in this place. The foregoing discussion will afford some indication of the number and type of the various phases included within the vacillans population which have been derived by gene-exchange with other diploid species. To attempt to give any sort of a precise definition to any of them would logically require that they all be given equal consideration, and I am not yet ready to attempt a definitive treatment of these forms, for the necessary data and materials are as yet inadequate. -While it may be temporarily inconvenient for the taxonomist to have such a polymorphic lot of material filed under a single name in the herbarium, this procedure may be better for the present than to have the subspecific nomenclature of the species further encumbered with tri- and quadrinomials such as those conceived by Ashe in an attempt to organize its local colmplexities.
There is perhaps an additional item which should be considered, that of the name for this complex. It is, obvious from the present text that a decision has been reached; however, the events leading up to it should be recorded. Some time ago, the author of this paper. published a short note wherein the name V. vacitlans was replaced by V. torreyanum (Camp, loc. cit). Before that, various collections had been matched by Dr. Smith against certain specimens deposited in English herbaria (footnote 2 of this paper). Dr. Smith's decision was that the specimen on which the name V. vacillans was based (as cited in Torrey's original description) was the equivalent of the type of V. pallidum Ait., which had clear priority. These facts seemingly required that the population here under discussion be given a valid name; hence the erection of the binomial V. torreyanum. However, it was intended that the circumscription of V. torreyanum be more limited than the present one of V. vactillans, being applicable to the material which appears here as the basic element of the complex. At that time it was also my intention to recognize such items as V. missouriense and V. mtargarettae, and possibly several additional now included in the complex.
Recently, Fernald (1943, p. 456, 457) took issue with the decision to replace the name V. vacillans by V. torreyanum, apparently being unaware of the similar nature of the type of V. pallidum and the supposed nomenclatural type of V. vacillans. Professor Fernald's argument that Torrey had never seen the specinen originally labeled "Vaccinium vacillans Kalm" can be disregarded, for it is a well-known fact that Torrey and various British botanists exchanged specimens and were in correspondence. The mere fact that Torrey was able to cite this specimen indicates clearly that he was aware of it and-considering the state of the knowledge of the group at that time-in possession of sufficiently accurate, information to place it reasonably well; at least he got it in a pair of species where decisions still must be made with care.
In the face of the foregoing it is seriously doubted whether Professor Fernald's decision would be upheld by a strict interpretation of the present Rules of Nomenclature, were it not for possibly extenuating circumstances. The facts are that the only specimen cited by Torrey in his description of V. vacillans is the one now in the British Museum, and that this specimen appears to be the biological equivalent of material better referred to the previously described V. pallidum Aiton. Although it seemed that the name V. vactllans could not be upheld, a review of the situation indicates that it may be possible to do so, but on somewhat different grounds than those proposed by Fernald. I have proceeded on the following basis: Although Torrey was quite unaware of it (as were his correspondents), and accepted it in good faith, it has beeli demolnstrated (Britten 1904) that the name written on this specimen-and attributed to Kalmwas spurious; that is, that Kalm was in no way associated either with the specimen or the name. Since it would seem unwise to accept this specimen as being valid because of the unfortunate eireumstances surrounding it, it is nmy present opinion that it may be ignored. However, as Professor Fernald points out, there would seem to be no need to drop the name V. vacillans; rather, it is here retainedo andl coupled with the single sheet in the Torrey Herbarium (in Herb. N. Y. Bot. Gard.) apparently collected by Torrey himself and so labeled. This also assists in clearing up another item in relation to the type of V. pallidum.
The authentic type of V. vacillains in the Torrey Herbarium is apparently clearly distinct from the type of V. palltidum. We still do not know the source of the material on which the latter was based, but in 1772 the settlements were already sufficiently close to the mountains, or even among them in parts of Virginia, Maryland, or Pennsylvania, that the good Doctor Martin would have had little trouble in obtaining material of V. pallidum as we have defilned it; or, as has been noted, reasonably pure material might have been collected at some distance from the mountains.
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