Affinities. Whether an order or sub-order this tribe certainly forms, through Hydrangeae, the connecting link between Saxifrageae and Myrtaceae, and seems even to render it probable that a more natural distribution would be, to unite Hydrangeae with Philadelpheae, and thus form an order intermediate but distinct from both. This, in fact, has already been partly accomplished by DeCandolle, who has placed Deutzia among his Hydrangeas, while all others, with one exception, place it in Philadelpheae. Bartling places it among his genera incertae sedis. This is merely thrown out as a suggestion not being myself in possession of materials to follow out the enquiry.
Geographical Distribution. Deutzia is found in Japan and India, Decumaria is an American genus, and Philadelphus is indigenous in Europe, America, and the north of India — Nothing seems to be known of their properties.
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.
