Art. XXXIV.—Note on Donatia novæ-zealandiæ, Hook, f.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 13, 1880, Page 289

Art. XXXIV.—Note on Donatia novæ-zealandiæ, Hook, f. By George M. Thomson, F.L.S. [Read before the Otago Institute, 29th June, 1880.] This interesting little plant, in the absence of the fruit, was placed originally by Sir J. D. Hooker in the order Saxifrageæ, and in his Handbook he speaks of it* “Handbook of the N.Z. Flora,” p. 58. as the only representative in New Zealand of the herbaceous tribe of Saxifrages proper. Up to within a very recent period, however, its exact systematic position was matter of considerable uncertainty. A few years ago, Baron Ferd. von Mueller expressed his decided opinion† “Fragmenta,” VIII., 39–41. that its resemblances were so near those of Phyllachne, that it should be placed along with that genus among the Stylidieæ, and this opinion he again published in Trimen's “Journal of Botany” for 1878, p. 174. In the absence of fruit, however, this affinity could not be considered as finally established. Mr. Petrie, Inspector of Schools for Otago, having recently obtained, at considerable trouble, numerous specimens of Donatia in fruit, forwarded them to Baron von Mueller, who has thus been enabled to prove his former assertions. It is to be regretted that Baron von Mueller in publishing the results of his last examination of the plant in question, should have elected to do so in an Italian journal, instead of in one accessible to the majority of those interested in the subject. The following description of the fruit and seed, together with the other information I record on the subject, is translated from “Dal Nuovo Giornale Botanico Italiano,” Vol. XI., N. 8, (July, 1879): “Fruit indehiscent, turbinate, completely bilocular, rarely trilocular, flat on the top and almost tumid on its margin, about 2 lines long. Placentæ short, situated almost at the apex or above the middle of the dissepiment. Seeds few in each loculus, rarely many ripening, pendulous or patent, attached without a funiculus, obliquely ovate or ellipsoid, ⅓—½ line long; testa membraneous, dark, shining, reticularly striated; hilum basal with the chalaza at the extremity more strongly coloured, almost brown; raphe not prominent; albumen amygdaline; embryo very small, remote or quite free from the hilum, often shorter than the albumen; cotyledons ovate-rotundate, almost equalling in length the central thin radicle, or the radicle united with the cotyledons into an almost ovate body.” Baron von Mueller regards the corolla of Donatia as gamopetalous, but having its tube shortened or suppressed, as occurs in the Rubiaceous genus Galium. The other points adduced are (1) the union of the stamens with

the style (as in the Stylidieæ), which, though not complete in Donatia, nevertheless places the filaments really in the centre of the flower, and entirely away from the calyx; (2) the minute embryo similar to that of Stylidium though its position may not be near the hilum; (3) the placentation, which is that of Stylidium, and not that of the normal Saxifrages; (4) the internal structure of the seeds, which agrees better with that of Stylidieæ than of Saxifrageæ; and (5) the normal number of two stamens in Donatia, which is not represented in any other Saxifrage. From these various considerations he places the genus among the Stylidieæ, of which the following enumeration of the known genera is given, which will prove useful to New Zealand botanists. Candollea, Labill. in Ann. du Mus. Paris, VI., 453, t. 63–64. Stylidium, Sw. in Willd. Spec. Plant. II. 146, an. 1805. Leeuvenhockia, R. Brown, Pr. 572. Phyllachne, R. and G. Forst. Char. Gen. 115, t. 58. Fostera, L. fil., in Nov. Act. Soc. Reg. Upsal, III., 184, t. 9. Donatia, R. and G. Forst. Char. Gen. 9, t. 5.