ENUMERATION OF MACADAMIA SPECIES

In the ninety-seven years between 1858 and 1955, several botanists added new species to Macadamia. Some of the species were described originally as species of Helicia, a genus so closely related to Macadamia that the distinctions between them are not clearly definitive. Several species described originally as members of another allied genus, Roupala, have also been transferred to Macadamia fairly recently. The history of transfers from Helicia to Macadamia, and sometimes back to Helicia, and of nomenclatorial changes among the Australian species of Macadamia is recounted in another paper (9).

Until 1952 when van Steenis (8) described a new species of Macadamia native to Celebes, thereby showing that its range extended to that island, the genus was considered to be strictly indigenous to a region of Australia encompassing only the eastern part of Queensland and the northeastern part of New South Wales. Its natural range was found to be further extended to New Caledonia with the transfer of three species to it from Roupala by Sleumer (6) in 1955.

The most recent revision of the genus, that by Sleumer (6) shows it as comprising nine species, five native to Australia, three native to New Caledonia, and one native of Celebes. Sleumer’s paper incorporates changes in typification and nomenclature proposed by Johnson (4) in 1954. it predates Smith’s (7) 1956 paper, however, and so does not include one species, M. integrifolia, which Smith restored to specific rank from its long regarded status as a botanical variety of M. ternifolia. In his paper, Smith also placed a different interpretation on the identification and typification of Mueller’s original M. ternifolia than did Johonson.

As presently understood, the genus Macadamia comprises 10 species. These are listed below as given by Sleumer (6) except that M. integrifolia which Sleumer did not recognize is included in the list and placed with its closest allies, M. ternifolia and M. tetraphylla. Authorities for the botanical names, synonyms, and type localities are given also.

1. M. whelani (F. M. Bail.) F. M. Bail., Queensl. Fl. 4: 1330. pl. 57, Jig. 2. 1901; Compr. Catal. Queensl. P1.: 440. 1913. Helicia whelani F. M. Bail., Rep. Exped. Bellenden-Ker: 55, diagn. 1889; Syn. Queensl. Fl. Third Suppl.: 61, 1890.Australia, N. E. Queensland.

2. M. hildebrandii Steen., Reinw. 1: 475. 1952.Celebes.

3. M. ternifolia F. Much., Trans. Phil. Inst. Victoria 2: 72, tab. 1958. Helicia ternifolia F. Muell., Fragm. Phytogr. Austral. 2:91. 1860Macadamia minor F. M. Bail. Queensi. Agric. Jour. 25: 11. 1910 __Macadamia lowii F. M. Bail., Queensl. Agric. Jour. 26: 127, pl. 15. 1911.Australia, S. E. Queensland.

4. M. integrifolia Maiden and Betche, Proc. Linn. SOC. New S. Wales 21: 624. 1897.—Macadamia ternifolia F. Muehl, var. integrifolia (Maiden and Betche) Maiden and Betche, Proc. Linn. Soc. New S. Wales 24: 150. 1899. Macadamia ternifolia F. Muell, cx Johnson, Proc. Linn. Soc. New S. Wales 79: 15. 1954.Australia, S. E. Queensland.

5. M. tetraphilla L. Johnson, Proc. Linn. Soc. New S. Wales 79: 15.

1954.Australia, N. E. New S. Wales, S. E. Queensland.

6. M. rousselii (Vieill.) Sleum., Blumea 8: 4. 1955.Roupala rousselii Vieill., Bul. Soc. Linn. Normand. 9: 394. 1865.; Guillaurn., Bul. Soc. Bot. Fr. 82: 277. 1935; Fl. Anal. Nouv. Caled. 1948: 103.New Caledonia.

9. M. prealta (F. Muell.) F. M. Bail., Queensl. Fl. 4: 1330, pl. 57, fig. 3. 1901; Compr. Catal. Queensl. P1.: 440. 1913 Helicia prealta F. Much., Fragm. Phytogr. Austral. 3: 37. 1862 Benth., Fl. Austral. 5: 404. J 870. Australia, N. New South Wales.

10. M. heyana (F. M. Bail.) Sleum. Blumea 8: .5. 1955. Helicia heyana F. M. Bail Queensl. Fl. 4: 1329. 1901; White, Contrib. Arnold Arb. 4: 22. 1933. Australia, N. E. Queensland.

In transferring Helicia heyana and the three New Caledonian species of Roupala to Macadamia, Sleumer (6) remarked as follows:

"Species similar to H. heyana in nervation are Roupala francii Guillaum. and R. veillardii Brogn and Gris. from New Caledonia which do not belong in Roupala, a purely South American genus revised recently by myself (Bot. jahrb. 76, 1954, 141). It is known since a long time, that both species and Roupala rousselii Vieihl., also from New Caledonia, have orthotropous ovules, hanging from the top of the cavity, which points to Macadamia, though, unfortunately, the structure of the fruits of these 3 New Caledonian species is unknown. I assume they should be assigned to Macadamia with which they agree in floral characters."

It may be noted that two species of long standing are now listed as synonyms of M. ternifolia in the enumeration above. These species are M. minor and M. lowii which Bailey (1, 2) described as new species in 191(1 and 1911, respectively. As early as 1929, Francis (3) doubted their standings as good species. Similar doubt was expressed by Johnson (4) in 1954. Sleumer (6) in his 1955 revision of the genus did not enumerate them as clear cut species but rather as synonyms of M. ternifolia, at the same lime noting that they are better regarded as variants of it than as separate species. And, Smith (7) in 1956 disposed of them with the statement "With the foregoing typification of M. ternifolia, it is considered that the names M. minor and M. lowii must now lapse into synonymy.

The species of Macadamia as listed above are placed according to affinities rather than alphabetically or according to the chronological order in which they were described. L. S. Smith, Botanist, informs me at the Botanic Museum and Herbarium, Botanic Gardens, Brisbane, through correspondence, that the Australian species of Macadamia with the addition of the species from Celebes are divisible into three distinct groups. The first group consists of M. whelani and M. hildebrandii, the second of M. tern ifolia, M. integrifolia, and M. tetraphylla, and the third of M. prealta and probably M. heyana. Presumably, the three New Caledonian species, M. rousselii, M. veillardii, and M. francii constitute a fourth distinct introgeneric group.

So far as I am aware, only M. integrifolia and M. tetraphylla produce palatable nuts. The remainder of the species have kernels which are ‘so bitter as to be inedible. Trees cultivated for the nuts under the name M. ternifolia actually represent either of the two species mentioned above. Although both are known variously as the Macadamia nut, Queensland nut, Australian nut, bush nut, Bauple nut (sometimes corrupted to Bopple and Popple), and nut oak, they are distinguished from each other by the names smooth-shelled and smooth-leafed for the former, and rough-shelled and rough-leafed or spiny-leafed for the latter. Mueller’s original M. ternifolia, variants of which became Bailey’s M. minor and M. lowii, now seems definitely identified as the species known in Queensland as the small-fruited Queensland nut, Maroochie nut, and Gympie nut.