The Genus Caltha in the Southern Hemisphere

The Genus Caltha in the Southern Hemisphere. BY ARTHUR W. HILL, M.A., Assistant Director, Royal Botanic Gardens, A'ew. With ten Figures in the Text HE genus Caltha, L., was subdivided by de Candolle (Syst., i, p. 307, T 1818) into two sections, Psychrophilax and Popnlago, the distinguishing feature being that in the former the calyx is persistent, while in the latter it is deciduous. Under the section Psychrophila he placed two species, C. appeitdicnlata, Pers., and C. sagittata, Cav., both from Antarctic South America, while the other section included all the Northern Hemisphere species. It is only with the Southern Hemisphere species that we are concerned in the present paper, and it will be shown that the peculiar foliage characters in these species—which extend from the high Andes of Ecuador to the Falkland Islands, Tasmania, Victoria, and New Zealand—mark them off as a peculiar and remarkable section of the genus more obviously than does the floral character originally noticed by de Candolle. Berchtold and Presl (Rostl. i. Ranunc, p. 80,1823) raised de Candolle's section Psychrophila to generic rank, which both Gay (Fl. Chil., i, p. 47) and Asa Gray2 also adopted. Gay gives descriptions of four species, the two additional ones being P. andicola (1. c, p. 49), and Hooker's Caltha. dioneaefolia, described in the London Journal of Botany, vol. ii, p. 306 (Gay, 1. c, p. 51). The general floral similarity of the Calthas from the Southern and Northern Hemispheres is so close that the establishment of a separate genus for the Southern forms would prove misleading, and Gay has not'been 1 The name is derived from tfnrxpot, cold, and <pi\iai. • The following note on the genus Psychropkila is given by Asa Gray in Botany U.S. Expl. Expedition, i,p. 13 :—Psychrophila: • Distinguished from Caltha as a genus by the nttmbranacecus, appendage 1r which terminate the thlckish sepals, either attenuated and as it were caudate, as in P. appendiculata, or short and blunt, as in P. dioneaefolia; by the few stamens (from 5 to 9) ; and the' few (a to 9) and i-8-ovttlale ovaries, and i-'i-seeded follicles; the suMuxcious flowers; and the very different habit. It must be confessed, however, that the New Zealand species of Caltha, recently, illustrated by Dr. HookeT, having narrow and attenuated sepals, is too nearly intermediate for the satisfactory discrimination of the two genera.' In the Genera Plantarum, i, p. 6, Psythrophila is maintained as a section of Caltha. Psychrophila, Rafin., Atl.Jonm. (1833), p. 144, refers to a Caltha from Oregon, and his two specific names P. auriculata and P. sagittata are not synonymous with Caltha sagittata, Cav., as the Index Kewensis rtates, apparently following Torrey in Ann. Lye. Nat. Hist, New York, ii, p. 164. • Rafinesqne's plant appears to be Caltha leploscpala, DC. [Annals of Botany, Vol. XXXTJL No. CXXVIL Jnly, iBi8.] 422 Mill.— The Genus Caltha in the Southern Hemisphere. followed by later writers; but it is convenient to relegate the Southern species to a separate section, for which the name Psychrophila may be maintained, on account of the peculiar development of the appendages of their leaves. Eleven species are recognized in the present paper, three being described for the first time. The new species, though collected many years back in the high Andes of Ecuador, Peru, and Bolivia, and in Tasmania, have apparently never received critical examination. The Andine plants have up till now been included under C. sagiftata, Cav., which is confined to the Magellanic region and the Falkland Islands,1 and the new Tasmanian species has been placed under C. introhba from Australia, from which, however, it is markedly distinct The characteristic feature of the plants belonging to the section Psychro- phila, as now understood, is the development of the auricles of the leaf laminae to form upturned or erect appendages, and this peculiarity is seen in its simplest form in C. sagittata and C. novae-zelandiae, Hook. f. In these two species the elongated auricles or lobes of the sagittate leaf are sharply folded up from the base, and the appendages thus formed either stand somewhat erect or lie partially over the face of the laminae with their under surfaces facing upwards. In C. andicala, Gay, and C.obtusa, Chessm., the appendages are so well developed that they are as a rule equal in size to the whole lamina. Excellent figures of the leaves are given by Cavanilles (Ic, v, PI. ccccxiv), and by Hooker in Bot. Mag., t. 4056, for C. sagittata; by Hooker for C. novae-zelandiae (Fl. Nov. Zeal., t. 6), and by Gay for C. andicola (Atlas Bot., PI. ii). The figures interspersed in this paper also illustrate the point, and are included to show the method of development of the more remarkable and distinct appendages of some of the other species. But for the existence of thesa simple forms of inflexion the morphological significance of the appendages in C. appendiculatat Pers. (see Deless., Ic, t 43), C. dioneaefolia, Hook. f. (see Fl. Antarct, ii, PI. lxxxiv), C. alata, A. W. Hill (Figs. 3 and 4), and C.phylloptera, A. W. Hill (Fig. 7), would be far from obvious. The next stage in the development of the appendage from the simple upturned lobe is shown by C. introloba, F. Muell. (Fig. 8), and C. involuta, A. W. Hill (Fig. 2). In the former species the axis of the fold is no longer at right angles to the petiole, but has become inclined obliquely to that organ at an angle of 450. The appendages are also considerably elongated towards the apex of the leaf, being produced forward over the surface of the lamina, and, as the fold lies partly open and is not pressed 1 Urban remark* (Eng. Bot. Jahrb. xxxvii, p. 401) that the genus Caltha is represented in collections from Colombia, Ecuador, and Chile by a widely distributed species, C. sagUtata, Cav. («= andicola, Gay). He thus failed to appreciate the morphological peculiarities of the leaves of the Northern Andine forms, and is also incorrect in reducing C. anduola, Gay, from Chile to the Magel- lanic species C. sagiitata, Cav. Hill.— The Genus Caltha in llie Southern Hemisphere. 423 down, the forward free portions of the appendages stand more or less on edge as erect, wing-like organs parallel to the midrib. In C. involuta the inclination of the axis of the fold has been carried a stage farther and has come to lie parallel to the petiole, so that the, appendage in this case is a lateral fold or flap instead of being a basal one as in C. sagittata, Cav. The explanation of the way in which this change in direction of the fold may have occurred would appear to be that the lobes of the leaf have grown basally and peripherally, thus resulting in a curvature of the- organ which has carried what was originally a basal infolding through a right angle, so that it has come to lie with the axis of the.fold parallel to the petiole and midrib of the leaf. If, further, the line of attachment of this lateral fold is carried forward, from the lobe of which it is a part, on to the lamina itself, so that it forms a distinct erect wing quite independent of the lobe, the condition represented by C. alata, A. W. Hill, from Bolivia, and C. phylloptera, A. W. Hill, from Tasmania, will be the result. Here the two wing-like appendages stand erect over the lamina parallel to the midrib and are attached for some two- thirds of their length to the lamina on either side of the midrib (see Chloris Andina, ii, PI. Ixxxiii B, under C. sagittata, and Figs. 3, 4, and 7). One of the most remarkable species is C. dwneaefolia, which has been so well described and figured by Hooker * and by Goebels that little more remains to be said. The two appendages arise from the base of the lamina and are wing-like organs covering the two halves of the lamina. As in C. alata, they represent laterally infolded lobes carried up on to the lamina, and their margins, like those of the deeply-bilobed lamina, are bordered with teeth resembling those of the genus Dionaea on a minute scale. The farthest extreme of the appendage development is shown by C. appendiculata and C. limbata, from the Magellanic region and S. Chile, where the appendages take the form of simple or lobed obovate-spathulate outgrowths from the upper surface of the somewhat similarly shaped laminae. - - — - ' - STRUCTURE 'OF THE LEAVES. - The leaves of these Southern Calthas show some features of interest in their internal structure, to which attention was first called by Goebel in the case of C. dioneaefolia. Here the stomata are confined to the morpho- logically upper surface of both laminae and appendages, on which side the feebly developed palisade tissue occurs. Possibly, as Goebel suggests, the closely infolded appendages form an air-chamber, and thus prevent the wetting of the stomata should the leaves of the plant be submerged. The 1 Hooker, J. D. : London Jonm. Bot., vol. ii, p. 306 ; Fl. Antarct., vol. ii, p. 229. 1 Goebel: Pflanzenbiol. Schild., vol. ii, 1891, p. 27, Fig. 6. 424 Hill.-—The Genus Caltha in tfie Southern Hemisphere. marginal teeth of the lamina and appendages would serve to render such tiny' air-chambers more efficient for the exclusion of water. Diels1 has further investigated the New Zealand species C. novae- ze-lattdiae and some of the S.

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