Orchidaceae Juss.
To date, there is only a single known occurrence of an indubitably adventive orchid - a plant of the European Dactylorchis maculata agg. found in a lawn at "Tutira" Hawkes Bay by H. Guthrie - Smith in 1937. Aside from floral differences this species is distinguished from all indigenous orchids by two vegetative characters - the ± palmately lobed or divided tubers, and the spotted leaves.
Chiloglottis formicifera
There is, however, a small group of Australian species -, Kaitaia, R. H. Matthews, 1901: Calochilus campestris, Aranga, north of Kaihu, R. Mason and N. T. Moar, 1949: Caleana minor, Rotorua, K.W. Allison, 1924 (Paracaleana minor (R. Br.) Blaxell Contr. N.S.W. Nat. Herb 4, 1972, 281): Pterostylis nutans, Whangaparoa Peninsula, L. M. Cranwell, 1942 - included in the indigenous flora on the basis of a few periodic occurrences in the Auckland district. The actual status of these, as also of the recently reported Cryptostylis subulata (Graham N.Z. J. Bot. 14, 1976, 275-7) from the same region is uncertain.
In view of the periodic large-scale movement of wind-borne dust, smoke, ash and burnt plant fragments from Australia to New Zealand it is possible that these five orchids of solitary or infrequent periodic occurrence are in fact casual adventives in New Zealand with their origin from dust-like wind-blown seed. However, it seems preferable to treat these species as members of the indigenous flora as their nativity remains uncertain, and all belong to a family well represented in New Zealand in which, moreover, most genera, except 3, are also recorded from Australia. On the other hand had plants, members of families not or poorly represented in our indigenous flora, and native to S. Africa, S. America or the Northern Hemisphere, been found here with similar distribution and sporadic appearance, they would almost certainly without question have been treated as adventive.
