Flora of New Zealand Series

Commonly known as green hoods, those with a long beak-like dorsal sepal as tutukiwi. Fls in some spp. are faintly sweet-scented.

Cheeseman (T.N.Z.I. 5, 1873, 352) described the pollination mechanism found in many spp., if not in all. At a slight touch, as by an insect entering the fl., the irritable labellum springs backwards so forming, with the column and its wings, a narrow tube. An imprisoned insect first passes over the stigma as it enters the tube from below and then meets in turn the rostellum and the pollinia as it emerges above. The sharp response of the labellum can easily be demonstrated experimentally in a fresh fl.

The genus has been subdivided by several authors each giving different weight to criteria that are, in part, difficult to define precisely. Robert Brown, after taking off spp. with an obtuse labellum-appendage, arranged those with a laciniate appendage according to the presence or absence of rosette lvs. The Sections of Bentham and Hooker are Antennaea, with inferior lip of perianth (i.e. connate lateral sepals) erect, concave, its lobes or caudae embracing the galea; and Catochilus, with inferior lip of perianth patent from the base or reflexed or recurved from the middle and also with obsolete or obtuse labellum-appendage. Rupp's (Proc. Linn. Soc. N.S.W. 58, 1933, 423) Sections Laminatae and Filiformae depend on the form of the labellum; Subsections are related to presence or absence of rosette lvs and relative importance of stem lvs, number of fls and features of lateral sepals.

In N.Z., only 3 spp. fall into Catochilus. In all the others the appendage is laciniate, the labellum laminate and the fl. normally solitary. Thirteen such spp. were recognized by Hatch (T.R.S.N.Z. 77, 1949, 234–246) and 9 of these he associated in 3 somewhat vaguely defined "Groups" of which one, the "Australis Group", is regarded as "a local development with no parallel in the other areas where the genus occurs"; spp. placed in this Group are: australis, montana and its var. rubricaulis, oliveri, areolata, banksii and its var. patens, graminea. Twisting of apex of labellum, to which Hatch attaches considerable importance, alters as fl. ages.

Leaves. In non-flowering plants of all spp., lvs tend to be crowded on a short stem and could therefore be said to be rosulate. If flowering plants are divided into, on the one hand, those that have basal lvs in rosettes followed by stem-lvs reduced to bracts and, on the other hand, those in which the stem-lvs above the membr. basal scales are all ± similar, a residue remains in which there is a gradual change from base to top of stem, while the spacing or crowding of the lower lvs varies with habitat. In the practical delimitation of such spp. it is convenient to use the concept of a "leaf spectrum", defined (Melville, Kew Bull. for 1952, 1952, 175) as "a gradation of leaf shape from those first formed on the renewal of growth of a shoot up to the apical leaves".

Perianth measurements. The height of the galea or hood is the distance from the top of the ovary to the highest point of the curving arch of the dorsal sepal, and is best measured up the side of the fl. The height of the dorsal sepal is usually the same measurement, but the total length of the dorsal sepal, measured along its mid-line, is always greater. In a flower of P. banksii, for instance, with a galea 3 cm. tall the dorsal sepal could be more than 7 cm. long and its narrow upturned tip could stand well above the top of the galea. In most spp. fl.-size reflects to some extent the vigour of the plant, and only approximate measurements can be given.

Lateral sepals. In descriptions of lateral sepals the "angle at which the lobes diverge" is that between the bases of the two lobes (sts called the sinus); where this is narrow, as in the majority of spp., the lobes themselves may still spread widely at a higher level. Sepal tips described as "caudate" or "almost filiform" are not solid; where the lamina is very narrow it becomes so deeply concave that the edges meet. There is thus every gradation between almost flat tips and the ± tubular ones referred to as caudae.

Fig. 27. PTEROSTYLIS. Lettering as in fig. 20, p. 103; La. a = labellum appendage; La. t = labellum-tip. © All rights reserved. [Image: 4X2J]

Fig. 28. PTEROSTYLIS. Lettering as in fig. 20, p. 103; La. a = labellum-appendage; La. t = labellum-tip; R-1 = rosette-leaves. Flowers shown with part of side cut away to display labellum and column. © All rights reserved. [Image: 4X2K]

Fig. 29. PTEROSTYLIS. Lettering as in fig. 20, p. 103. La. a = labellum-appendage; La. t = labellum-tip. Flowers shown with part of side cut away to display labellum and column. © All rights reserved. [Image: 4X2L]