Illustrations of Indian Botany, Vol. 2/Onagrariae

by Robert Wight

LXVI.—ONAGRARIÆ.

This, like the preceding, is an order on the limits of which Botanists seem greatly to differ in opinion; some, Brown, DeCandolle, &c, considering Onagrariae and Halorageae distinct orders, while others, Lindley and Mei3ner, view them as parts of one more extensive group, which they call ONAGRACIÆ including, according to the former, (Lindley) as sub-orders — Circeae, Hydrocaryes, and Halorageae; to which Meisner adds, Callitrichineae and Ceratophylleae. But of these Lindley disposes very differently, by sending Callitrichineae as a distinct order to the imperfect flowered division of the system, while he views Ceratophylleae as a sub order of Urticeae. Endlicher (genera plantarum) on the other hand retains both as distinct orders, placing them along with Podostemmeae near Piperaceae.

In the midst of these conflicting opinions I confess myself altogether incompetent to decide which is right, but will adopt a middle course. With this view I retain Onagrariae and Halorageae as distinct orders, but exclude Callitrichineae from the latter, as I formerly did Ceratophylleae from Salicareae, both to be afterwards considered along with Podostemmeae, specimens of a species of which I have received from both Ceylon and the Neilgherries, further, viewing the genera Circœa and Trapa as sufficiently distinct from all those of the true Onagrariae to warrant their partial separation, I shall follow Lindley in considering these as sub-orders.

Thus limited, this order includes only two genera from the south of India, Jassiœa and Ludwigia, though it is probable Epilobium will yet be added, as some species of it are found on the Himalayas, and I think I have seen one from Ceylon and another from the Neilgherries, but probably introduced.

Of Circœa I have one species from the Neilgherries and Pulney mountains. Trapa has been long known in India.

Most of the true Onagrariae are herbaceous plants or tender shrubs, with angular or round stems and opposite or alternate simple leaves, either sessile, or attenuated at the base into a short petiol, often dentate or serrated, but rarely pinnatifid, dotless and exstipulate. In the few met with in India they are quite entire. The flowers are bi-sexual, regular, axillary and solitary, or racemose and, with scarcely an exception, all the parts regular multiples of two, four being the prevalent number.

The following is Dr. Lindley's character of the order.

"Calyx superior, tubular, with the limb 4-lobed ; the lobes cohering in various degrees, with a valvate æstivation. Petals generally equal in number to the lobes of the calyx, into the throat of which they are inserted, regular, with a twisted æstivation. Stamens four or eight inserted into the calyx: filaments distinct; pollen triangular, usually cohering by threads. Ovary of several cells, generally crowned by a disk ; style filiform ; stigma either capitate or 4-lobed. Fruit baccate or capsular, many-seeded, with 4 cells. Seeds numerous, without albumen ; embryo straight ; radicle long and taper; cotyledons very short. Herbaceous plants or shrubs. Leaves alternate or opposite, simple, entire or toothed. Flowers red, purple, white, blue, or yellow, axillary or terminal."

Affinities. In habit they are allied to Salicareae, from which they are distinguished by their ovary cohering with the tube of the calyx, not free as in them.

They also approach Myrtaceae through Fuschia, hut differ in the ahsence of pellucid dots and in having definite stamens. This last character equally distinguishes tliem from Philadelp/ieae. The filiform style and ahsence of albumen separate them from Halorageae, from which they also differ in habit. They have also been compared with Loaseae but are readily distinguished by their binary, not quinary, arrangement of the parts of the flower which mark that order, leaving altogether out of consideration the acrid stinging properties possessed by Loaseae.

Geographical Distribution. The species of this order are numerous, amounting according to DeCandolle's I'rodromus to 24S. including Trapa and Circcea, the greater p or . tion of which are American, though, to some extent, found in all countries from the extreme north, through every degree of latitude, to the equator, ami thence nearly 50 degrees south, but most abound in the temperate regions. In India, within the tropics, the species are few and except Ludwigia paroiflora and Jussitea repens, of rather rare occurrence. In the more temper- ate regions of the Himalayas thirteen species of Eptlobium have been found, one of which has been figured by Dr. Royle.

Properties and Uses. Of these almost nothing is known. The roots of the evening primrose jEnotkera biennis are edible, and it is cultivated for their sake.

Remarks on Genera and Species. In an order containing only two genera within the limits to which this work extends, there is not much room for remark on this division of the subject, yet I cannot altogether pass it over, as I think we have more genera than we can find good characters for. Jussicea is readily distinguished by having twice as many stamens as petals, but in both Ludwigia and Isnardia they are the same, and in truth, so far as I can discover, there is no good difference between these genera, the plant here figured, which is unquestionably a Ludwigia, seems to agree equally well with the character of Isnardia.

EXPLANATION OF PLATE 101.

Ludwigia parviflora.

1. Small plant — natural size.

2. Expanded flower.

3. Stamens.

4. Capsule cut transversely.

5. Ovary cut longitudinally.

6. Mature capsule splitting, showing the ripe seed.

7. Ovary cut transversely, 4-celled, with several rows of ovules in each — all more or less magnified. Nos. 4 and 7, are misplaced.

SUB-ORDER CIRCÆEÆ.

This sub-order consists of but one genus, essentially distinguished from all the true Onagrariae on the one side, by the cells of its ovary having only one ovule, and from Hydrocaryes on the other, by its ovules being erect not pendulous.

From Halorageae it is equally distinguished by its erect, not pendulous, ovules, and still further by its ex-albuminous seed. The following is Lindley's character of both the sub-order and genus.

" Calyx superior, deciduous, tubular, with a two- parted limb. Petals 2, alternate with the lobes of the calyx. Stamens 2, alternate with the petals, inserted into the calyx. Disk large, cup-shaped, filling up the whole of the tube of the calyx, and projecting beyond it. Ovary 2 (or 1) celled, with an erect ovule in each cell ; style simple, arising out of the disk ; stigma emarginate. Fruit 2 (or 1) celled, 2-valved, 2 (or 1) seeded. Seeds solitary, erect ; albumen none ; embryo erect ; radicle short, inferior. Herbaceous plants. Leaves opposite, toothed, stalked. Flowers in terminal and lateral racemes, covered with uncinate hairs."

Affinities. These have been already pointed out under the preceding order.

Geographical Distribution. They have only been found in the northern hemisphere. The species though few in number, have a wide range over the northern regions of Europe, America and Asia— Royle has figured one from the Himalayas and I have one from both the

Neilgherry and Pulney mountains. Royle considers his a new species and has called it C. cordata, mine does not appear to differ specifically from C. alpina, either in character, habit, or in the kind of locality where it grows.

Remarks on Species. It is almost amusing to peruse the characters by which Botanists, ever since the days of Linnæus, have been endeavouring to distinguish between C. lutetiana and C. alpina, which neither individually nor collectively would, in any doubtful case, enable any one, except by chance, to tell the one from the other, even though the species are certainly distinct. The genus until extended by Indian additions consisted of those two species only, the fruit of the former of which is 2-celled, with an erect seed in each cell, hence the generic character " ovarium 2-celled with an erect ovulum in each cell : fruit 2-celled, 2-valved, 2-seeded. Such being the case in one species it is inferred it must equally be so in the other, and the flower being small and fruit rarely produced, this is taken for granted. By taking it for granted Botanists have puzzled themselves in vain, for at least a century, to find good specific characters by which to distinguish them. The ovary at once supplies the long sought-for desideratum."

Ovary 2-celled — C. lutetiana.

Ovary 1 -celled — C. alpina.

EXPLANATION OF PLATE 101* OR 112.

Circœa alpina.

1 . Plant — natural size.

2. A flower, front view.

3. Flower and ovary, side view.

4. Stamens.

5. Stigma.

6. Detached ovary.

7. Cut transversely.

8. Cut vertically, showing the erect ovule — all more or less magnified.

Sub-order Hydrocaryes.

This sub-order, like the last, consists of only one genus, Trapa, and differs essentially from it in the position of its ovules — erect in that, pendulous in this. They are floating plants, always found in water. The Indian species T. bispinosa is so very rare a plant, in southern India, that I have only once seen it growing and that on the Malabar Coast. The sub-order is thus characterized by Lindley.

"Calyx superior, 4-parted. Petals 4, arising from the throat of the calyx. Stamens 4, alternate with the last. Ovary 2-celled ; ovules solitary, pendulous ; style filiform, thickened at the base ; stigma capitate. Fruit hard, indehiscent, 1-celled, 1-seeded, crowned by the indurated segments of the calyx. Seed solitary, large, pendulous ; albumen none ; cotyledons 2, very unequal. Floating plants. Lower leaves opposite, upper alternate ; those under water cut into capillary segments ; petioles tumid in the middle. Flowers small, axillary."

The species of this genus, 5 in number, are all natives of Europe and Asia, one is a native of Europe, 2 of India proper, one of China, and one of Cochin China.

Properties and Uses. " The great seeds of Trapa are sweet and eatable. Those of T bispinosa form an extensive article of cultivation in Cashmere and other parts of the east, where they are a common food, under the name of Singhara nuts." — Lindley.

ONAGRARIÆ.

LUDWIGIA PARVIFLORA (ROXB.)

CIRCÆEÆ. ONAGRARIÆ.

CIRCÆA ALPINA.