This charming spring flower called in popular language Rue-Anemone,
indigenous to eastern North America, has been known from early times,
and as in many other equally unfortunate cases has had imposed upon it
by botanists a superfluity of scientific names. Linnaeus in his Species
Plantarum, 1753, listed it as Anemone thalictroides; in 1803 Michaux
called it Thalictrum anemonoides; it was rechristened as Syndesmon
thalictroides in 1832 by Hoffmansegg; finally Spach in 1839 proposed the
name Anemonella thalictroides. Botanists to-day consider our plant as
more properly placed in Hoffmansegg’s genus Syndesmon, and for it the
earliest specific name, applied by Linnaeus, is very properly retained;
hence the correct designation in botanical language is Syndesmon
thalictroides (L.) Hoffmg.
The extent of variation in this plant has been but partially noted
heretofore. The tabulation given below indicates the results of
observations made the latter part of April and the first of May this
year in regard to the number of flowers and the variation in the
involucral leaves. As to whether these are sessile as given in our
Manuals, notes have appeared on previous pages of this Journal by
Messrs. Burglehaus, Wetzstein and Schaffner, cf. pp. 72, 104 and 106.
[Illustration:
Fig. 1. Diagrams showing arrangement of leaves and flowers.
]
The number of flowers is normally three and the involucral leaves two. A
diagram showing their arrangement is given at A, Fig. 1. The two leaves
are not always ternate; they may both be simple, diagrammatically shown
at B. A further variation, shown in Fig. 1 C presents one simple and one
compound leaf. At D greater complexity is indicated, there being in many
plants besides the central flower three instead of only two axillary
ones, and only one of the subtending leaves is compound. In the case
shown at E two of the three involucral leaves are compound. As shown in
F and G four leaves may contribute to form the involucre and each one
subtend a flower; in some cases two of the leaves are compound, in
others three or even all may be compound. Still other variations along
this line occur, but space forbids a fuller enumeration.
It should be stated that although the pedicels and leaves as shown in
the diagrams (Fig. 1) occupy but a small portion of the circle, as a
matter of fact the leaflets are spread and so disposed as to occupy the
entire area when viewed from above the plant, the leaflets being
equidistant from each other, or contiguous but not overlapping, and
therefore taking the most advantageous position so far as sunlight is
concerned.
The very striking variation in regard to presence or absence of the
petiole to the involucral leaves has been previously noted. An
inspection of a very large number of specimens collected in the vicinity
of Columbus and in Perry and Logan counties, as well as of specimens
kindly sent for the purpose by Mr. F. H. Burglehaus, Prof. A. Wetzstein,
and Supt. H. N. Mertz, shows that petiolate forms occur exclusively in
some localities (Northwestern Ohio); in other places the sessile form
only obtains (Eastern Ohio); and yet elsewhere both forms are about
equally represented (Central Ohio). We can not regard the petiolate
forms as in any real sense a variety (much less a distinct
species)—since both sessile and petiolate leaves occur in countless
cases on the same plant. But where the petiolate form occurs
prevailingly or may be exclusively, it would be advantageous to
designate the same; therefore I propose as follows:
Syndesmon thalictroides f. PETIOLATA nova forma. Involucral leaves
prevailingly or exclusively with petioles 2–10 or even 25 or more
millimeters in length; otherwise like the typical species. Toledo (F. H.
Burglehaus), St. Marys (A. Wetzstein) and West Mansfield, occasionally
at Columbus and Rendville.
Comparatively few monstrosities were observed. In one case only did
merely one leaf and two flowers occur; often but one flower develops
though two leaves occur as usual; in a few cases a single small leaf was
seen on a pedicel. A more common teratological variation was the
elongation of the axis at the usual point of insertion of the flowers
and involucral leaves, often distantly separating the leaves with their
axillary flowers; in one case the distance between the points of
insertion of the leaves was nearly two inches. The sepals are
occasionally excessively numerous.
A characteristic very prominent is the similarity of the several stems
that come from the same root. If one presents the typical form of
flowers and leaves almost without exception, the second (and third when
present) do the same; if one varies in any respect rarely does the
remainder fail to follow suit. This can be seen in the tabulation where
two or more stems are indicated—both or all are given (except in Nos.
29, 30 and 49) as observed, in the successive serial numbers. Another
instance of the persistency of an idiosyncracy, as we may call it, was
observed in some Syndesmons taken from the woods by a gardener at
Springfield, Ohio, over forty years ago. The flowers were bountifully
double, and the plants have each year since faithfully presented the
same striking peculiarity.
The tabulation that follows is based on specimens from Toledo (Lucas
Co.), Nos. 1–30; from St. Marys (Auglaize Co.), Nos. 31–48; from
Steubenville (Jefferson Co.), Nos. 49–65; from West Mansfield (Logan
Co.), Nos. 66–76; from Rendville (Perry Co.), Nos. 77–88; and from
Columbus, Nos. 89–100. The number of stems to each plant is given in the
second column; then follow in order the number of flowers to each stem,
the number of simple leaves with length of their petioles in
_millimeters_, the number of compound leaves with length (also in
_millimeters_) of their petioles and finally of their petiolules.