The Journal of Indian Botany/Volume 2/January 1921/Drought Resisting Plants in the Deccan

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DROUGHT RESISTING PLANTS IN THE DECCAN.

By R. K. Bhide.

Assistant Economic Botanist, Bombay.

The drought of 1918-19 in the Bombay Deccan was one of the most long-continued and severe on record. While the normal rainfall over most of the area lies between 20 and 30 inches per annum — though it is much higher than this in the west — the actual rainfall for 1918 was in most cases between one third and one half of this amount, and of the quantity received a very considerable proportion was received in one or two fitful storms in May and August or September J 918. The actual condition of things in five typical centres, given in order from west to east is shown in the following table : —

The result of this long-continued drought was that in 1918 the usual wild monsoon plants did not grow well, or if they grew at all most of them died before seeding or seeded before they were half grown. The country never looked green, and, except for the trees which remained green, was a desert-like waste in the latter part of 1918 and the earlier part of 1919. Even the most resistant plants suffered. In some places it was reported that Babul trees {Acacia arabica Willd.) had died. As a matter of fact many of the Banian trees (Ficus benga- lensis L) especially those which happened to be growing on road sides near dry hills showed an unusual leaf-fall and remained practically bare of leaves for some time. Even the very resistant prickly pear [Opuntia nigricans Haw.) showed signs of suffering, and in April 1919 had taken on a yellow colour and was drooping over extensive areas. It seemed a matter of some interest under these very exceptional conditions to ascertain what plants remained actually alive and grow- ing, and to find the amount of available moisture round the roots of such plants. The enquiry did not concern itself with trees, but only with herbaceous and sub-woody plants, and particular attention was devoted to (l) finding out to what degree the moisture conditions can be reduced, without preventing the wild indigenous weeds, mostly of arable land, from living and growing (2) *noting the general behaviour of the plants or the particular adaptation of the different plant- organs which seemed to enable the plants to tide over the drought, and (3) making special notes of any plants of agricultural or other economic value (especially of fodder value) that lived and grew through the drought, so that they might be tried as additions to the drought resisting plants actually grown in the country. This last aspect of the study was considered to be of very great importance, for shortness of fodder is now the great characteristic of famines in the Deccan.

A chain of stations was made across the Deccan, and working from these all the plants, whether likely to be of use or no, which were living and growing at the hottest and driest part of 1919 in the month of May were secured, and in many cases samples of the soil in which they were growing were collected for a moisture determina- tion. The samples of soil were taken, chiefly from the lower one third of the root region.

Moisture determination in the soil thus collected gave some difficulty. It was obvious that a mere determination of the loss on heating in a steam bath would not give the actual amount of "free" water in the soil, — and it is the "free" water that it was important to

• In doing this a comparison of the herbarium material of the difierent species collected from time to time in different situations as regards rainfall and soil, conditions was made, with the plants now collected to see what deviations from the normal type could be detected in each case. And although we cannot rely solely upon such a comparison in determining the behaviour of a plant in a particular situation under different conditions of soil moisture still in the absence of any direct comparison, that was the only course left open. estimate. To get as close as possible to an idea of the actually available water for the plants, the soil was dried at 45 to 50 c. on a sand bath till the weight was constant.

The survey, as already stated, was made in May 1919. It must be pointed out, however, that before the observations and notes were completed, there had been slight rain in a few places. But this rain rarely amounted to more than a few hundredths of an inch.

The principal plants found living and growing under the condi- tions of extreme drought described are shown in the following list : —

1. Polygonum plebejum B. Br. — This was found on medium black sticky soil at Talegaon * on May 1, 1919. The available moisture round the roots was about 3,00 per cent.

An examination of the herbarium material of the species shows that under different rainfall or soil conditions the species varies a great deal as regards the size of the plant, the length of the internodes, and the size of the leaves.

As collected now it was a very small prostrate or diffuse plant scarcely half an inch above the ground, branched from near the base, branches barely reaching an inch in length. The root was slender, Xa inch in diameter, and 3 — 4 inches in length. It had no lateral bran- ches. The leaves were very minute, scarcely i inch in diameter. The plant was in flower and showed some purple anthocyanin pigment.

Beduction of the size of the plant and of the leaves to about i-i of the well developed size is therefore the only response of the plant in the present abnormal conditions.

2. Chrozophora prostrata Dalz. — Bather common. This was found on medium black, sticky soil at Talegaon, on May 1, 1919. The available moisture round the roots was about 3'00 per cent.

This plant also seems to vary much in different places, as regards the length of the branches and the size of leaves.

As collected now it was a small prostrate plant, scarcoly an inch above the ground. The root was slender, ro inch in diameter and 5 — -6 inches in length, devoid of lateral branches. Branches of the stem were 1 — 2 inches long, and leaves stellately hairy. The leaves were ir — j inch long and broad. The plant was in fruit. It had also developed some anthocyanin pigment in the stem and leaves.

Thus reduction in size is apparently the only response of the plant in the present conditions.

3, Solatium xanthocarpum Schl. — Bather common. It was found on medium black soil which was somewhat more sticky

• The rainfall of Talegaon is closely similar to that shown above for Vadgaon. than in the case of Nos. 1 and 2 at Talegaon, on May 1, 1919. The

available moisture round the roots was about 3*50 per cent.

In different situations the plant shows slight variation as regards the size of the leaves and their prickliness.

In the present instance it showed practically no deviation from the average plant. It had a tap root 9 — 10 inches long and i inch in diameter.

4. Argemone mexicana L. — Bather common. This spiny leafed plant was found under similar conditions to No. 3 at Talegaon on May 1, 1919. Available moisture round the roots was about 3'50 per cent.

Except for the size, the plant shows no appreciable difference in different situations.

In the present instance also it did not show any deviation from the normal type. The root was a tap root about 9 — 10 inches long and 3 — 2 inch in diameter, divided in the lower half into two slender branches about 5 — i inch in diameter.

At Talegaon and on the same day as the above plants were examined, the following plants were also noticed occupying a rugged place ; no samples of soil were however taken in their case : —

Euphorbia neriifolia Linn, — Several plants showing a sickly yellow colour and no leaves.

Bombax malabaricum DC— In a leafless condition.

Opuntia nigricans Haw, — Several plants with a yellowish colour and thin flaccid looking phylloclades.

Gymnosporia Rothiana Laws. — In a practically leafless con- dition.

Flueggia leucopyrus Willcl.— -In a practically leafless condi- tion.

Lantana indica Boxb. — In a practically leafless condition.

Vitis Woodrowii Stapf. — In a leafless condition, but the young leafbuds were just sprouting.

A.cacia arabica Willd. — Practically in the normal condition.

It may be noted that all these plants are perennial and with the exception of the Acacia and Opuntia (in which latter the leaves are absent) loss of leaves was their chief device for tiding over the drought.

5. Lepidagathis trinervis Nees — var. asperrima ?— Bather common in the place. It was found in a light grey coarse soil (murum) with a layer of dust above, in an open barren situation, at Belapur* on May 6, 1919. The soil round the roots contained 1*28 per cent. of available moisture.

• The rainfall here is not unlike that at Ahmednagar or at Snevgaon

above recorded. The species seems to vary much as regards the size of the plant or its leanness. It also shows some variation as regards having two kinds of roots, viz. fibrous roots in addition to the tap root in various situations, (possibly this is also true in the case of several other plants mentioned in this list, though perhaps to a less extent than in the present case).

As collected here the plant had a diffuse woody stem covered with very small cuspidate leafy bracts provided with rough hairs. The tap root was woody, about 6 — 8 inches long and ^ inch in diameter with numerous fine rootlets or feeding roots near the surface of the soil where they came in contact with the dust. The plant was in fruit.

In the present instance the practical absence of leaves, presence of numerous feeding roots in addition to the woody tap root and the possession of hairs on the minute leafy organs (reduced bracts ?) seems to be the plant's response to the drought conditions.

6. Tephrosia purpurea Pers.— The plant is common in the tract. It was found in light grey coarse soil (murum) in an open barren situation, at Belapur, on May 6, 1919. The soil round the roots contained 1*38 per cent, of available moisture.

The species varies to some extent as regards the size of the plant, the size and number of leaflets, and the hairiness of the plant in different situations.

In the present instance reduced size and some suppression of the leaflets seems to be the only response of the plant. The root of the plant was a tap root 8 — 9 inches long, about inch in diameter, with several small lateral branches.

7. Zizyphus xylopyra Willd.— This prickly plant is very com- mon in the tract. It was found at Belapur on May 6, 1919 on light grey poor soil in an uncultivable place. The soil round the roots contained 1'89 per cent, of available moisture.

It varies a great deal as regards the size of the plant and of the leaves according to situation. In favourable situations it grows into a tree.

In the present instance the plant was scarcely three feet high and had very small loaves about | — f inch in diameter. It was much branched from near the base. It had a long tap root f inch in dia- meter with several laterals which spread somewhat horizontally.

A mere reduction in size was therefore the response though not necessarily an unusual response of this plant. Often in ordinary times also the species does not assume larger dimensions in this tract.

8. Tragia cannabina L. — This occurred at Belapur on May 6, 1919, in deep black very sticky soil, which round the roots of this plant contained 3.36 per cent, of available moisture. .

The plant varies a good deal as regards the size of the leaves and their hairiness.

As collected here the plant was about 6 — 8 inches in height. It was thickly covered with stiff and stinging hairs The root stock was thick about § inch in diameter, soon divided into several rather stout lateral root-branches about 1 — 2 feet long and spreading obliquely. The leaves were tripartite to the base with narrow and divided lobes which were about an inch long and §- inch broad. The plant was not in flower or fruit.

Thus the hairiness of the leaves had increased and their size was reduced to at least I — i the size to be found in favourably placed plants.

9. Echinops echinatus Roxb,— This prickly plant with cot- tony under surface of the leaf is very common in the tract. It was found on light grey coarse soil (murum) on uncultivable land. The soil round the roots contained 1.55 per cent, of available moisture.

The plant only shows some little variation as regards the size it attains in different situations, and in the present instance it only showed a slight reduction in the same. Its root was a tap root 6 — 8 inches long and | inch in diameter devoid of lateral branches.

10. Leptadenia reticulata W. £ .4. — This was found in medium black or brownish soil of rather sticky character, at Belapur, on May 7, 1919. The soil round the roots contained 2.33 per cent, of available moisture.

The plant varies a great deal as regards the size of the leaves in various situations. The leaves have accordingly become very small in the present instance. They only attained f — 1 by | — inch. The plant was peculiar in having a root about lu feet long and — § inch in diameter. The root stock was about an inch and a half in dia- meter and gave rise to several branches of the stem. The root spread horizontally about six inches below the surface of the soil and had a few long and slender branches. The old root and the old part of the stem had a rough and deeply cracked corky bark. The leaves of this plant are used as a vegetable in times of scarcity by the poorer people.

11. Cucumis trigOilUS Roxb.— This was found in medium black, sticky soil at Belapur, on May 7, 1919. The soil round the roots contained 2'59 per cent, of moisture.

The plant seems to vary much as regards the length of the branches and the size, division and hairiness of the leaves, in differ- ent situations.

In the present instance also the size of leaves is reduced to | — | pf the usual size and their division and hairiness seem to be more than the average. The branches of the plant also were fewer and much shorter. The root of the plant was peculiar. It was about two feet long and i inch in diameter over the greater part of its length and practically without lateral branches.

12. Tridax procumbens L.— Very common. It was found on brown rather sticky soil at Belapur on May 7, 1919. The soil round the roots contained 2'61 per cent, of available moisture.

In different situations the plant varies as regards the length of the branches, the size of the loaves, and their hairiness.

In the present instance the size of the leaves was slightly re- duced and the hairiness somewhat more accentuated than usual. The root was a slender tap root 6 — 9 inches long and about § inch in diameter, devoid of lateral branches, but with a few minute feeding roots in the lower half.

13. Vernonia cioerea Less. — Common. It was found on brown rather sticky soil at Belapur, on May 7, 1919. The soil round the roots contained 2'24 per cent, of available moisture.

The plant shows variation as regards size in different situations, and in the present instance also the plants were shorter and the leaves smaller, the root was a tap root 6 — 9 inches long and about i — g inch in thickness, apparently without any lateral branches.

14. Cocculus villosus DC— Common. It was found on light to medium black soil which was not sticky, at Belapur, on May 7, 1919. The soil round the roots contained 2"22 per cent, of available moisture.

This plant also showed only reduction in the length of the stem branches and in the leaf surface as usual. The root of the plant was about a foot and a half long and about | — 3 inch in diameter apparently without any lateral branches.

15. Morinda tinctoria Boxb.— var. tomentosa. It was found in medium black sticky soil at Newasa * in the Ahmednagar district, on May 8, 1919. The soil round the roots contained 3.93 per cent, of available moisture.

The plant grows into a shrub or small tree, and in the present instance the plant was apparently a root-sucker. There were several other similar root suckers close by. They showed no deviation from the normal. The root was long, about I inch in diameter with slender laterals spreading about eight inches below the soil.

16. Caralluma fimbriata Wall— It was found on May 8, 1919, at Newasa in a limy soil which though dusty was inclined to be sticky, and contained round the roots 202 per cent, of available moisture.

• Rainfall comparable with that of Shevgaon as shown above.

The plant did not show any deviation from the normal type. Leaflessness, succulence, and the possession of a number of small feeding roots seem torenable the plant to overcome drought. The root was about 4 — 6 inches long. There were also numerous small feeding roots arising from part of the stem which came in contact with the dusty soil. It may be noted that the plant is used by the poorer classes as a vegetable in times of scarcity.

17. Fagonia cretica L. — Rather common. This prickly under- shrub was found at Newasa on May 8, 1919, on light grey, somewhat sandy soil, containing flakes of mica. The soil round the roots contained at that time 2'06 per cent, of available moisture.

The plant shows slight variation in size in different situations. A practically leafless condition of the plant due to the reduction of the leaf-surface and the general reduction in size are characters which enable the plant to stand drought. The root was a slender tap root 6 — 8 inches long and about !• inch in diameter with one or two slender laterals in the lower half.

18. Heliotropium supinum L — It was found in sticky silt containing Kankar nodules in a dry stream at Newasa, on ' May 8, 1919. The soil round the roots contained 2'46 per cent, of available moisture.

The plant shows some variation as regards the size in different situations. In the present instance it only showed a slightly reduced size as compared with the normal type. The root was slender, 6 — 7 inches long and | inch in diameter, devoid of lateral branches.

19. Alysicarpus rugosus var. styracifolius Baker.— This was found in a sandy soil in a dry stream at Newasa on May 8, 1919. The soil round the roots only contained 0'80 per cent, of available moisture.

In the present instance the plant only shows a great reduction in size as it usually does in dry situations. It was only 3 — 4 inches high The root was a slender tap root 4 — 5 inches long and about rt> inch in diameter, divided into two branches and a few very small lateral rootlets.

20. Trichodesma indicum Br — Rather common. It was found on light yellow or brown soil at Shevgaon on May 9, 1919. The soil round the roots contained 1'70 per cent, of available moisture.

The plant shows praotically no deviation from the normal beyond some reduction in size as is usual with it in such conditions. Its root was a slender tap root about 8 — 10 inches long and J — £ inch in diameter with several slender laterals spreading horizontally.

21. Celosia argentea L. — It was found on light, yellow or brown soil, at Shevgaon on May 9, 1919. The soil round the roots contained 1'65 per cent, of available moisture.

The plant varies a great deal as regards its height and the size of leaves in different situations.

In the present instance it showed an extreme reduction of all the parts, the plant being scarcely three inches high though in flower. The flowering spike was scarcely k inch long. The root was a slender tap root 5 — >6 inches long.

It may be noted that the plant is used as a vegetable by the poorer classes in times of scarcity.

22. Heliotropium zeylanicum Law— It was found in light yellow to brown soil at Shevgaon on May 9, 1919. The soil round the roots contained 1'56 per cent, of available moisture.

The plant responded to the present conditions by undergoing a reduction in the size of the leaves to about — £ that of the well developed ones, as is usual with the plant in such circumstances. The root was a tap root about If feet long and i inch in diameter devoid of lateral branches in the upper half.

23. Taverniera nummularia. DC— Rather common in the place. It was found in deep black sticky soil between Shevgaon and Babhulgaon on May 10, 1919. The soil round the roots contained 3'38 per cent, of available moisture.

The plant was 8 — 10 inches high and very much branched. It showed a distinct reduction of the leaf surface to about — i as com- pared with the well developed specimens, which seems to be its usual response under similar conditions. The root was a tap root a foot long and f inch in diameter with two to three laterals placed at intervals and spreading more or less horizontally.

24. Citrullus colocynthis Schrad.—lt was found in sandy soil in the bed of a dry stream between Shevgaon and Babhulgaon on May 10, 1919. The soil round the roots contained only 0"93 per cent, of available moisture.

The plant seems to respond to such arid conditions by reducing the size of the leaves to f — i and by producing more numerous stout, bulbous-based hairs on the under side of the leaf. It has done the same thing under the present conditions, and has produced a tap root about 18 inches long and about h inch in diameter.

25. Balanites Roxburghii Planch.— Common. This thorny plant was found in brownish sticky soil between Shevgaon and Pathardi* on May 11, 1919. The soil round the roots contained 3'04 per cent, of available moisture.

• The rainfall at Pathardi and Babhulgaon is practically the same as at Shevgaon.

The plant seems to respond only by slightly reducing the size of the leaves as usual in such cases. The root was a tap root about two feet long and £-| inch in diameter. The present plant was a bush about a foot high but it grows into a shrub or small tree afterwards.

26. Trianthema pentandra L. — It was found on light yellow to brown soil at Babhulgaon* on May 12, 1919. The soil round the roots contained 1*41 per cent, of available moisture.

As usual in such cases the size of the plant showed reduction which in the present one was very great. The plant was diffuse scarcely an inch in height or in the length of its branches. The leaves were ■"?- by inch, slightly fleshy in texture. The root was a slen- der tap root 4-5 inches long, bifurcated at the apex.

27. Boerhaavia diffusa L. — Rather common in poor soils. It was found on light grey coarse soil (murum) on the side of a hill at Sirur on May 21, 1919. The soil round the roots contained 1*20 per cent, of available moisture.

As usual with the plant in extreme cases a very great suppression amounting nearly to practical absence of the leafy parts, a reduction of the size of the leaves and the possession of a very thick rather long or conical tap root was the response of the plant in the present in- stance.

28. Dipcadi montanum Dalz.— Rather common in the place. It was found in light coarse soil (murum) on the side of a hill at Sirur on May 22, 1919. The soil round the root contained 2*53 per cent, of available moisture.

Perennial nature and ability to remain dormant are characteristics of the plant that enable it to tide over unfavourable times.

The plant as usual had a tunicated bulb and slender fibrous roots ; having just fruited it was passing into a condition of rest. It was therefore leafless at the time.

29. Cyathocline lyrata Gxss. — It was found in medium black rather sticky soil at Parner on May 23, 1919. The soil round the roots contained 2'45 per cent, of available moisture.

This species shows great variation as regards the hairiness of the leaves in different situations. In the present instance the plant was densely hairy. It had apparently finished fruiting long ago and was probably sprouting from the dormant cottony buds found in the lower axils on the stem. This might possibly be due to some rain which had fallen at Parner, a few days previous to the date of collection.

30. AndropOgon monticola Schultz. — Found in light grey coarse soil (murum) on the slopes of a hill at Sirur on May 21, 1919.

• The rainfall at Pathardi and Babhulgaon is practically the same as at Shevgaon.