40.

SOME TAXONOMIC TERMS DEFINED - R.C. Close.

ii very short time spent identifying New Zealand is sufficient to show the prevalence cf hybridism in our flora. The literature on our flora contains many terms which apply to this and to other features of . Thus it is necessary that their purpose and limitations should te well understood, The following terms are, therefore, presented: Specie s: That stage in the evolutionary process where forms become segregated into two or more separate arrays, physiologically incapable cf inter-breeding. The main factor that separates species is isol• ation. This can be genetical, reproductive, ecological or geograph• ical . Jordanon: A true breeding group of similar individuals, distinct from any other such 'group. Simple species: * jordanon to which specific rank has been given and which is not closely related to any other jordanon. e.g. Agathis australis. Compound species: Two or more closely related jordanons, which it has been convenient to unite together under the one name, e.g. Rubus australis. Variety: Any jordanon of a compound species sufficiently distinct from any other of the jordanons so as to allow it to be effectively diagnosed, e.g. Macropiper excelsum var, pei tta,corum, Linnean: A compound species, frequently in a very wide sense, to• gether with all the hybrids between its jordanons and their epharm• ones, e.g. Cyathodes acerosa, leptospermum scoparium, Olearia arborescens, Hebe salicifolia. It may include "more than one species. Epharmone: An unstable form of a jordanon which is due te environ• mental influence and differs markedly from the so-called !'usual or normal" form. Cf course the normal form is as much an epharmone as any other, but it is generally the most abundant, e.g. Senecic lautus has lowland, montane and alpine epharmones. I8fffl: ^n indefinite term, applied for convenience to an individual of unknown status. Ty_pe: Refers to the original described material, i.e. the first valid publication cf the name and description, Cultigen: For a form of unknown origin, found only in cultivation, e.g. Nothopanax macintyrei, Hybrid: This involves a cross between plants cf different status, e.g. we have inter-jordanic, inter-specific and intergeneric hybrids. Hybrid swarms: Indicates all the individuals which occur between two species, e.g. there is a range of forms between Melicope simplex and M. ternata, some being nearer to one species than the other. These hybrids, known as M. x tersimplsx are to be found in the Waitakeres. Similarly the hybrid forms between Corokia buddleoides and C. coton• easter, Coprosma propinqua and C. robusta are to be found at Huia. These hybrid forms are in some cases so distinct that they have been 1*1. • •• . * described as species, e.g. in the Corokia, the hybrid is des• cribed in Cheeseman (19251 as C. cheesemanii (Carse), while the Coprosma hybrid has been described as C. cunninghamii (Hook.). Similarly the cross between Myrtus bullata and M. obcordata has been known as M. ralphii. The hybrid forms between Danthonia pilosa and D. semiannularis are known as P.. .x semi pilosa, and the many forms between Hebe elliptica and H. Salicifolia are known as B. x ellipsala. Polymorphy: The different parts, of an individual , e.g. leaves, flowers, stipules, may vary greatly. Similarly among groups of closely-related individuals, there may be differences in the form of the various plants making up the group, i.e. at a particular time. Thus polymorphy is the variation which occurs within individual plants or within species. Examples of Ibis are given by Cockayne and alien (1927). Phenology. The condition where different species and even varieties have different flowering period. The study of this in relation to

the New Zealand flora has been relatively neglected and much remains to be clarified. Homoblastic species: These are plants in which the leaf-form and habit does net vary throughout the life-history, e.g. Geniostoma ligustrifolium. Heteroblastic spp. Those which possess a distinct juvenile form with a change to the adult, e.g. Carmichaelia spp. Seme species fruit while still in the juvenile form, e.g. Parsonsia heterophylla. Others such as Blechnum filiforme do not reproduce until the adult form is attained.

The following terms are of more recent introduction: Ecotypes: All the members of species that are fitted to survive in a particular environment within the total range of the species. Ecotypes confined to a particular habitat—they are still inter- fertile but differ morphologically.

Ecospecies: 0 All the ecotypes genetically so related that they are able to exchange genes freely without loss of fertility or vigour in the offspring. Coenospecies: All the ecospecies so related that they may exchange genes among themselves to a limited extent through hybridisation. Comparium: All the coenospecies between which hybridisation is poss• ible either directly or through intermediates, sterile hybrids are generally produced.

No hybrids can be produced between members of different comparia. This terminology is of recent origin and if adopted would change our genera to coenospecies. A Comparium would be equal to a group of genera:

Ewartia Helichrysum COMPARIUM

Raoulia — Leucogenes 42.

DIVERGENT SPECIATION

Comparium Comparium - no crossing at all. \ — — -* Coenospecies - sterile hybrids, no gene exchange. Coenospecies Ecospecies - P. hybrids are obtained and a certain amount of Ecospecies gene exchange is possible.

Ecotype Ecotype - crossing possible and the a products are fertile.

The. taxonomy of Ne w Zealand's native plants is greatly complicated by hybridism, In considering the vascular plants alone, we find more than 300 groups of hybrids, these occurring in the ferns, conifers, grasses, sedges, orchids, beeches and many other well- known groups (Cockayne, 1929 a). This vast amount of hybridism will naturally upset our identifi cation of a specimen, but at the same time it provides many intere sting problems which need clarification. In certain genera hybridism is more rife than in others. A list of these is given below: Asplenium (numerous hybrids, especially between A. bulbiferum and others. Hypolepis. Podocarpus. Uncinia. Pterostylis (many around Auckland) Nothofagus. Muehlenbeckia. Clematis, Pittosporum, ('numerous hybrids) Rubus. Coriaria (species, when they occur Nothopanax. together, hybridise abundantly, Coprosma (identification of large- as at Mt. Egmont). leaved forms in Auckland area is Alseuosmia (very difficult genus, confused by hybridism). , the exact status of many of its Olearia. species is not elucidated). An interesting example of a hybrid is that between Metrosideros robusta and M. tomentosa. This is to be found on Rangitoto Is. A thorough study of the life-histories of plants is of importance to taxonomy, e.g. a marked distinction in the juvenile form separates Sophora tetraptera (no juvenile form) from S. microphylla which has a distinct prostrate juvenile stage. About 200 species of New Zealand plants show more or less strongly marked dimorphy or even polymorphy as they go from the juvenile to the adult stage. these changes may be abrupt or gradual. CClassica l examples of heteroblasty occur in Parsonsia. Carmichaelia, Pseudo- panax, Phyllocladus, Podocarpus dacrydioides, Scheffler_a aan: d many other genera. An interesting example of jordanons and their relation to heteroblasty is provided by Leucopogon fasciculatus. There are probably in this species two jordanons, one of which possesses a juvenile stage. Because of the lack of investigation neither has been elevated to varietal status. A similar condition probably exists in Schefflera. Also important to taxonomy is the herbarium and the experi• mental garden. The latter is generally neglected but it serves a great purpose in elucidating many problems relating to hybridism. Collected materia] may be grown so as to find the suspected parents. Epharmones, or suspected ones, can be planted to see how they react to changed conditions. The herbarium, on the other hand, must be consulted frequently. But obviously no collection of herbarium specimens, however complete, is satisfactory without the added in• formation from field studies and experimental cultures. Thus the 43. revision of a genus must be carried out in the field as well as in the laboratory. A good introduction to taxonomy in relation to the New Zealand flora is to be found in a paper by Cockayne and Allan (1927). All the scientific names used in this article are those. ... in Cheeseman (1925). References. Cockayne, L. 1923. Hybridism in the N.Z. Flora. New Phyt., XXII (3), 105. Pamph. 575.12. and 1927. The Bearing of Ecological Studies on Allan, H.H. Botanical Taxonomic Conceptions and Procedure, Journ.Ecol., XV(2), 234-77. Cockayne', L. 1929a.Hybridism in the Forests of New Zealand. Acta Forestalia Fennica, 34, 1-23. Pamph. No. 575.12. 1929b.Die Vegetation der Erde, XIV. Vegetation of New Zealand. Liepzig. In English.

CELMISIA CORIACEA Hook. - T.C. Chambers.

During a combined Field Club- Department excursion to National Park in May, 1949, one plant of Celmisia coriacea was found growing near the Lower Tama Lake. This species has not previously been recorded from National Park, On Mt, Egmont G. W. Mason has also found two plants together in flower under Tahurangi Bluff (4,500 ft.), also a new record. On the distribution of this plant Cheeseman says— "North Island: Reported from the Tararua Mountains by Buchanan, but I have seen no specimens from thence. South Island: Abundant throughout in a number of districts, especially in the central and western portions of the Southern, Alps. Altitudinal range 1,500—4,500 ft." He continues: "A truly noble plant, probably the finest species of the genus. In its most luxuriant state it has a short stout stem which with the old leaf-sheath is sometimes as thick as the wrist, and is crowned with numerous spreading and erect leaves from among which arise one or several stout scapes (sometimes branched), bearing heads sometimes more than 3 inches diameter with long narrow rays." In February and May of 1951 further visits were made to the plant at Tama Lake and it appears to be thriving with several small vegetative offshoots but there was no sign of any flower. Photographs were tahea and these should be of great interest for future comparisons. It is possible that there are other, as yet undiscovered, plants of this species at National Park, but if so they are certainly not common. If there are no other fruiting plants in the area it is certainly interesting how the seed travelled such a long distance and settled in such a suitable alpine environment.