A redefinitionof Gastonia and related genera (Araliaceae) W.R. Philipson Department of Botany, University of Canterbury, New Zealand Summary and The six genera Gastonia, Tetraplasandra, Reynoldsia, Munroidendron, Peekeliopanax, Indokingia form a natural complex distributed from East Africa to the Marquesas and the Hawaiian Islands. The characters in these The between which have been thoughtuseful distinguishing genera are re-examined. distinction in Gastonia and Tetraplasandra is redefined, emphasis being placed on the radiating stigmatic arms the On is Hawaiian fruit rather than onpleiomery ofthe stamens. this basis Tetraplasandra confined to the group. The monotypic genera Peekeliopanax and Indokingia are reduced to synonymy under Gastonia, which thus comprises all species of the complex west of Samoa. Introduction Araliads leaves with the with imparipinnate and pedicels no articulation between pedicel and the flower form with a clearly defined group a nearly continuous distribution from East Africa, through the islands of the Indian Ocean and Malesia, to the Solomons, limits Samoa, the Society Islands, the Marquesas, and the Hawaiian group. Generic within natural have this is this group of species always been confused, and especially true the Malesian of the been in area. Here, at the centre range, species have referred to genera characteristic of the Pacific or the Indian Ocean according to the characters available in the material being studied. The reason underlying much of this confusion is undoubtedly that the fruit of Gastonia the flower found Comm. ex Lamk is distinctive, having radiating stigmatic arms, and that in many species of Tetraplasandra A. Gray is also distinctive, having numerous stamens. In the Malesian and some other species these two features occur together. This has resulted of winkleri in fruiting material being described as species Gastonia. G. papuana Miq., G. and boridiana floral On Harms, G. Harms were all described from specimens lacking parts. the other hand, flowering material(with the exception of G. eupteronoides Teysm. & Binn.) has been described either as Tetraplasandra (T. paucidens Miq., T. philippinensis Merr., T. solomonensis Philipson, and T. koordersii Harms) or as the new monotypic genus Peekeliopanax Harms. Indeed, Miquel described flowering and fruiting material of the and same species as a Tetraplasandra a Gastonia on consecutive pages and-Harms described and several later described another species as Peekeliopanax from flowering material, years a fruiting specimen of the same species as a Gastonia. In the present study the characters which have been used to diagnose the genera within of The this complex species have been re-examined. species are currently placed in six diree of three These in genera, moderate size and monotypic. are set out Table I. The of the char- remarks included in the last column ofTableI are intended to indicate some acters at used delimit the These and other characters will be discussed present to genera. in the account. of of the Tetraplasandra following For purposes presentation data, genus has been This regarded as confined to the Hawaiian Islands. practice is justifiable because BLUMEA 498 VOL. XVIII, No. 2, 1970 the all Malesian Tetraplasandra can be referred to existing species of Gastonia. This course in no way prejudices any decisions on generic limits that may be drawn after the data have been presented. TABLE 1. GENERA CURRENTLY RECOGNIZED Number Genus Distribution Remarks of spp. Gastonia 7 East Africa, Madagascar, At present defined by the Seychelles, Mascarenes, radiating stigmatic aims in Malesia, Solomons. the fruit, and the stamens (supposedly) equal in number to the corolla segments. Hawaiian not radiate in Tetraplasandra 19 group (Malesian Stigmatic arms and Solomons spp. exclu- fruit, some spp. with pleio- ded — see text). mery of the stamens, ovary cells rather few (10—)5—2, and leaflets entire. Reynoldsia 17 Hawaiian group, Marque- Stigmatic aims not radiate in sas, Society Islands, fruit, stamens equal in number Samoa. to rather petals, ovaiy cells numerous (6—)10—24, leaves without rarely some denticula- tions. Hawaiian radiate in Munroidendron 1 group. Stigmas not fruit, stamens not more than corolla ribs, ovaiy cells about 13, inflorescence branches long- -racemose. (un- Peekeliopanax 1 New Britain, New Guinea, Radiating stigmatic arms Solomons. known when described), corolla calyptrate, stamens numerous. Indokingia 1 Seychelles. Radiating stigmatic arms with cleft tips, corolla calyp- trate, stamens numerous. DESCRIPTION OF THE CHARACTERS Vegetative morphology the with clustered ends All species are trees imparipinnate exstipulate leaves at the of branches. thick The majority are glabrous but the single species ofPeekeliopanax Harms and MunroidendronSherffhave indumentum do hawaiiensis as Tetraplasandra A. Gray, T. kauaiensis (H. Mann) Sherff, and T. turbans Sherff. The margin of the leaflets is entire in A. Munroidendron and also in most G. Tetraplasandra Gray, Sherff, Gastonias. papuana from both conditions the varies entire to strongly crenate, occurring at two extremes of wide the leaflets The its range. In Peekeliopanax are crenate, usually strongly so. leaflets of the of borne Hawaiian species Reynoldsia A. Gray are distinctive, being on R. Philipson: A W. redefinition of Gastonia and related genera (Araliaceae) 499 with the lamina when long petioles papery in texture dry, somewhat rhomboidal in undulate The southern of shape, and with an and dentate margin. species Reynoldsia have varied from those similar the Hawaiian more leaflets, ranging to type to leaflets approach- those ing found in the other genera of the complex (e.g. R. pleiosperma A. Gray). The inflorescence The inflorescences terminate the take leafy shoots. They may four main forms: i) The branches be as of principal may strictly umbellate, in species Tetraplasandra with twice or thrice umbellate inflorescences (fig. i) and this character recurs in Reynoldsia verrucosa A in these is for Seem. (Society Islands). 2) more common arrangement genera the main be branches (rhachids) to umbellately arranged, but for the ultimate umbellules to be borne along them in a racemose or subverticillate manner (fig. 2). Such inflorescences also occur in Peekeliopanax and Indokingia Hemsl. 3) Internodes may develop between the the branches nodes bearing main (fig. 3), giving a paniculate inflorescence (e.g. internodes between Gastonia papuana). 4) Finally, may develop all, or at least the outer of the these (lower) pedicels ultimate flower clusters, so that are not umbellules but are less in more or distinctly racemose (fig. 4). This character appears a few species of Tetra- the plasandra and Reynoldsia. In Munroidendron long pendulous rhachids bear very striking racemosely arranged flowers. The pedicel One important character that distinguishes this group of genera from Polyscias Forst. and the lack of a between the flower and the of the its allies is constriction top pedicel. In Polyscias there is an articulation below the flower which is clearly visible in fresh material flowers and fruits. In fresh material of the considered such of yoimg genera being no articulation is visible. However, in dried material of flowers of a few species a constriction the of is the tissue the occurs at top the pedicel. This due to the drying of fleshy at base material these become and the ofthe hypanthium. In fruiting tissues stronger constriction This artifact become noticeable no longer develops on drying. can so in some species [e.g. Tetraplasandra waialealea Rock, T. meiandra (Hillebr.) Harms and T. kauaiensis] that identifications incorrect may occur. The calyx The consist rim entire calyx may of a with the margin and straight or irregularly of if the undulate. In most species Tetraplasandra, not all, undulations form more regular lobes, usually alternating with the petals, and each bearing a minute apical tooth. In of Reynoldsia any suggestion oflobing or toothing the calyx rim is even more obscure and and irregular. In Gastonia Peekeliopanax undulations of the calyx rim, when present, are irregular. I have been unable to check this feature in Indokingia. The corolla The features of the corolla similar the general are throughout group, being those typical of the Schefflereae. Those features which are variable, and which will be considered of here, are the number of petals and the degree their separation. the of observed the of Table 2 indicates range merism in genera. The numbers petals relate either the less united of the corolla. to the free petals or to more or segments Complete fusion occurs in Indokingia Hemsl. In Peekeliopanax the corolla is also calyp- reach of trate, but sutures which do not the outer surface the cap are clearly developed. The of Munroidendron free or united into The of petals are variously groups. petals BLUMEA VOL. No. 500 XVIII, 2, 1970 Inflorescence — umbel. — Fig. 1—4. types. 1. Tetraplasandra meiandra, compound 2. Peekeliopanax — spectabilis, an umbellate arrangement of racemes of umbels. — 3. Gastonia papuana, panicle. 4. Reynoldsia sandwicensis, ultimate branches. W. R. Philipson: A Castonia and related redefinition of genera (AraHaceae) 501 TABLE 2. MERISTIC VARIATION IN GENERA ALLIED TO GASTONIA Petals or Genus Stamens Ovary cells corolla segments Gastonia 5—13 7—55 7—12 Tetraplasandra 5—9 5 —60 2—10 Reynoldsia 8—12 8—12 6 —24 Munroidendron 16—20 5 —20 12—14 Peekeliopanax 6—12 25—66 6—22 Indolcingia 6 93 13 and be Gastonia, Tetraplasandra Reynoldsia do not appear to united organically, but frequently fail to separate completely. The number of stamens In Reynoldsia stamens equal the petals in number and alternate regularly with them do (Table 2), as they also in some species of Gastonia (e.g. G. cutispongia Lamk) and in In these Tetraplasandra (e.g. spp. 14—19 Sherff, 1955). other species of two genera the androecium is pleiomerous (e.g. Gastonia seychellarum Baker has five petals and eighteen G. is with stamens and papuana extremely variable, 7 to 55 stamens). variable with —66. has been Peekeliopanax is equally 25 It possible to make only one of the the result The count stamens in Indokingia, being 93.