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The Journal of Indian Botany/Volume 1/September 1919/On Alysicarpus Rugosus D. C. and its Allied Species

ON ALYSICARPUS RUGOSUS D. C. AND ITS ALLIED SPECIES.

BY

L. J. Sedgwick, F. L. S.


It is a well-known crux whether the extremely diverse forms of Alysicarpus which show a lomentum with the joints deeply and closely transversely rugose belong to one species or several. De Candolle (Prodr. I, 353) described two species, — A. styracifolius and A. rugosus. Wight and Arnott (Prodr. I, 234) gave three, viz., A. styracifolius of De Candolle, and two new ones of their own, — A. Wallichii and A. Heyneanus. Baker (F. B. I. II, 159) reduced all previous descriptions and all known specimens to one variable species, for which he retained the name A. rugosus D.C., making A. styracifolius D.C. and A. Heyneanus Wt. & Arn. varieties, along with a third variety ludens from the specific A. ludens of Wallich, and regarding Wight and Arnott's A. Wallichii as a synonym of the type. Later floras (so far as known to me) have followed Baker, several other varietal names, however, having been added, viz., minor and pilifer both of Prain, and probably others.

While not denying that many of our Indian species need reduction, being merely local or edaphic forms, I am disposed to think that the Indian Floras have often on the other hand given a wholly exaggerated impression of morphological variability (as opposed to plastic reaction to environment) through failure to detect the definite characters dividing closely allied species ; and this would seem to be the prevalent view at the present time. In particular I am convinced that where in the same habitat two clearly distinguishable forms exist side by side and do not merge they must necessarily be true species. For this reason the field worker is an indispensable complement to the herbarium systematist, inasmuch as he is able to observe the innumerable plants around him, and note their demeanour.

The fact that A. rugosus D.C, as understood since the F. B. I., contains more than one species has been forced upon me by field observations at various camps in the Dharwar District during the last three seasons. For instance this winter on the black soil east of Hubli, M. S. M. Ry., two quite distinct plants were abundant as weeds in the fields. Their differences amounted to at least six characters. Over a wide tract of country there must have been millions of these plants, and out of the enormous number which came under observation during a month and more no individuals were seen which could not be at once allocated (even from horse-back) to one or other of the two types. Now if these types were intra-specific, then their contrasting characters would be allelomorphs. I regret that it did not at the time occur to me to observe the methods of fertilisation ; but there is reason to expect that a typical papilionaceous flower with diadelphous stamens is liable to cross-fertilisation. If so, and if the contrasting characters were allelomorphs, then the occurrence of two separate types each of them exhibiting the whole set of contrasting characters, without the occurrence of even one individual which could be classed as heterozygotic in even one pair of characters, would, I suppose, be an impossibility. However, even if Alysicarpus were shown always to be self-fertilised, still the absolute constancy and uniformity of these two sets of characters in the same environment would, I fancy, have convinced anyone who had seen them that we have here two species.

In a single homogeneous tract like the black soil referred to the habit of a species is likely to remain fairly constant. But there is little doubt that most of the species of Alysicarpus are highly plastic and react strongly to environment ; and this plasticity is probably the main cause of the confusion which now exists as regards the species with the rugose lomentum, since the superficial (somatic) differences between individuals of the same species are often more obvious than the morphological (germinal) differences between the species.

The systematic notes which follow are based on the field observations referred to as well as on the material in the herbarium of Mr. T. R. D. Bell, CLE., and myself, and the material in the herbarium of the St. Xavier's College, Bombay, collected by Father Blatter and Mr. Hallberg, and very kindly placed at my disposal by those gentlemen. This material is all from Western India at various points from Mt. Abu to Madura. It will be seen that I discriminate three certain and one probable species. But I should be far from suggesting that a study of material from the whole of India would not necessitate the recognition of further species. This paper is intended to be suggestive only, and is published in the hope that other workers may find it of use in a further and more complete study of this particular systematic problem. Especially has it been quite out of the question to attempt the unravelling of the intricate synonymy of these plants ; indeed it is doubtful whether this work could be done anywhere but in Europe, where alone the numerous type sheets may still be available.

1. A. styracifolius D.C.

Prostrate, or with geniculately ascending branches, (possibly sometimes erect ?). All parts covered both with short pubescence and longer stiff opaque white hairs. General colour of the leaves dark leaden-green, contrasting strongly with the pale racemes. Racemes short, dense. Calyx paler than straw-colour ; segments ovate acuminate, usually with an indurated tip, closely ciliate throughout their length with straight erect white hairs. Lomentum usually exserted.

Herb. Sedgwick and Bell.

No. 1801. Coimbatore, Aug. 1916.

2010. Black soil fields, Kunemelihalli, Dharwar Dist. Dec. 1916.

5274, 5278, 5281, 5283 to 5289. Black soil fields, Feb. 1919. east of Hubli.

5308, 5336. Fields, Sherewad Dharwar District. do.

5697. Gokak, Belgaum District, March 1919.

Herb. St. Xavier College, Bombay.

631. Kamban, Madura District, May 1917,

8843. Tapti R. Banks, Khandesh, Dec. 1916.

8855. Dangri, Khandesh, do.

8788. Khandesh, do.

10086. Muravad, Khandesh, do.

12385, 12394, 12395. Bhusaval, Khandesh, do.

This species seems to be much less variable than the others. It is usually fairly easy to pick out in herbaria from the strong contrast between the dark leaves and pale racemes.

2. A. Heyneanus Wt. & Am.

Usually erect, rarely procumbent with geniculately ascending branches often very tall and robust. Stem clothed all over with pubescence and spreading hairs. General colour of leaves ordinary green. Raceme3 variable in length and density, but usually long lax and narrow. Calyx straw-coloured ; segments oblong subacute, with a few white hairs or not. Lomentum usually prominently exserted.

Herb. Sedgwick and Bell.

No. 2034. Yelvigi, dry regions of the Dharwar District, Dec. 1916.

2087. Kunernelihalli, Dharwar District, on black soil, do.

3675. Forty miles south of Dharwar, Feb. 1918.

3840. Chabbi, Dharwar District, do.

5269, 5270, 5272, to 5277, 5279, 5282. Black soil fields, Feb. 1919. east of Hubli,

5313 to 5315, 5337. Fields, Sherewad, Dharwar District, do.

5441. Dangs, Gujarat (very robust), do.

5486. Tegur, Dharwar District (very robust), March 1919.

Herb. St. Xavier College, Bombay.

10195. Taver, Khandesh, Dec. 1916.

22684. Antorli, Khandesh, do.

8813, 8814, Tapti R. Khandesh, do.

8787. Antorli, Khandesh, do.

10102. Paldhi, Khandesh, do.

8853. Khandesh, do.

8852. Tapti R. Khandesh, do.

8844. Muraval, Khandesh, do.

9376. Lina Hill, Nasik, Sep. 1917.

8784. Bombay Island, (short, but with v. lax racemes), Nov. 1916.

8786. Igatpuri, Western Ghats, (a form similar to the last), Jan 1917.

8805. Igatpuri, (tall and with v. lax racemes), do.

12849. Turanmal, Satpuras, 'Khandesh, (an old state, Dec. 1918. very robust with very long racemes).

This species is highly variable in habit.

3. A. rugosus : D.C.

Usually prostrate, but sometimes erect. Stem glabrous except for a single alternating line of oppressed ascending hairs. General colour of leaves ordinary green. Racemes short dense. Calyx straw-coloured ; segments long, oblong, subobtuse, glabrous, or ciliate at the tip only with short, often purplish hairs. Lomentum usually inclined.

Herb. Sedwick and Bell.

1846. Mugad, Dharwar District, Oct. 1916.

2155. Dharwar, Nov. 1916.

4366. Dharwar, Sept. 1918.

4438. Konankeri, Dharwar District, Oct. 1918.

Herb. St. Xavier College, Bombay.

No. 12858 and 12827. Sea-shore, Alibag, Konkan (Coll. by Feb. 1917. Moses Ezekiel).

12862. Bice-fields, Alibag, (Coll. as the last), do.

8798. Salsette, Bombay, Nov. 1918.

8778, 8774 and 9383, Mt. Abu. Oct. 1916.

8848. Bombay, Nov. 1916.

8834. Salsette, Bombay, Sept. 1916.

8803. Purandar Fort, Poona District, Dec. 1917.

12829. Poona,

9370. Bassein, North Konjan (tall), Sept. 1918.

9385. Bassein, (tall, but with short racemes), Sept. 1917.

12686 and 12688. Campoli, (v. tall, with racemes Oct. 1918. 2 inches long),

4. A. ludens Wall, {probably).

Tall, erect. Stems with line of hairs as the last. General colour of leaves ordinary green. Bacemes exceedingly long and lax, with distant flowers in pedecillate clusters.

Herb. St. Xavier College, Bombay.

No. 12691. Khandala, October, 1918.

A working clavis would be as follows : —

Stems pubescent and with spreading hairs,

Leaves dark leaden-green, racemes dense, calyx segments acuminate, strongly ciliate A. styracifolius DC.
Leaves ordinary green, racemes lax, narrow, calyx segments subacute, with or without a few hairs . . A. heyneanus W. & A.

Stems glabrous except for an alternating line of oppressed ascending hairs,

Racemes short, dense A. rugosus, DC.
Racemes very elongate, lax, with distant fasicles of pedicillate

flowers A. ludens Wall.

It is necessary however to remark that with age both the vestiture of the first two species and the line of hairs of the last two are deciduous.