Flora of New Zealand Series

Type sp., P. tenax.

Fls bisexual. Infl. terminal; peduncle long, sheathed with a series of alt., deciduous bracts of progressively smaller size, the lower ones empty, the upper ones each subtending and entirely enclosing a comparatively short, alternately branched, flowering lateral; smaller bracts quite scarious. Pedicels articulate just below fl. Fls ± zygomorphic. Tepals subequal, erect, forming a tube but connate only near base, c. 12-nerved, marcescent. Stamens > tepals; filaments glab., only slightly flattened, inserted in pit along back of anther; inner filaments a little longer than outer; anthers linear-oblong. Ovary superior, sessile, elongate; ovules ∞; style terete; stigma small, narrow. Fr. a long capsule, loculicidal. Seeds ∞, flattened, almost winged, black, shining. Tall, perennial, tufted plants, increasing by budding from stout rhizome. Lvs crowded in distichous fans, linear-ensiform, equitant, strongly keeled, marked by ∞, fine, close longitudinal striations and strengthened by tough bast fibres. Two spp., one endemic to N.Z., the other found also in Norfolk Id.

The taxonomic position of Phormium has been discussed since Hutchinson (Fam. Flow. Plants 2, 1934, 153; 2, 1959, 664) included it in Agavaceae. According to Cave (Lilloa 31, 1962, 179), "comparison of two of his tribes, Yucceae and Agaveae, with Phormium, the only genus of the tribe Phormicae, shows how they differ in delimitation of microspores, apertures in the wall of the pollen grains, the presence of cover cell, the nucellar cap, the hypostase, and the mature megagametophyte." Cave further points out that Phormium deviates from the other members of the family in being the only genus with (1) equitant distichous lvs and (2) 16 as the basic chromosome number, and suggests that the genus be excluded from the Agavaceae, proper placement being deferred until more information is available.

The very characteristic branching of the infl. is referred to by Cave as sympodial, but this is hardly an adequate description. Fls open in regular sequence, the flowering laterals maturing acropetally. Within each lateral the first fl. to open is the one furthest from the main axis, i.e. at the end of the first order branch, Similarly the fl. terminating the second order branch opens before that on the third order branch, etc. Each branch arises in the axil of a bract.

The two spp. of Phormium (Hair and Beuzenberg, N.Z. J. Bot. 4, 1966, 266) do not display such a pronounced bimodality of chromosome content as has been reported in the tribes Yucceae and Agaveae (Granick, Amer. J. Bot. 31, 1944, 283–298), the range being c. 3:1, as in Cordyline.

Shorland (N.Z. Sci. Rev. 21, 1963, 62–63) reports that work on lf-hydrocarbons clearly separates Phormium (n C 29) from Cordyline (n C 27).

The wide N.Z. literature on Phormium deals largely with the extraction and use of the fibres for cordage, textiles, etc. B. D. Cross (T.N.Z.I. 47, 1915, 61–66) records a detailed study of many forms of the two spp. Allan and Zotov (N.Z. J. Sci. Tech. 18, 1937, 799-804) report on an artificial cross between P. tenax and P. colensoi, and Allan and Cranwell (Rec. Auck. Inst. Mus. 2, 1942, 269–279) discuss inheritance of aberrant behaviour in which, in place of some or all of the fls, an infl. produces lfy buds or "vivipars". Results of extensive breeding programmes associated with commercial growing areas near Foxton, including interspecific crosses, are mentioned incidentally in connection with yellow-leaf disease (Boyce and Newhook, N.Z. J. Sci. Tech. 34A, Suppl. 1, 1953, 10). A thorough modern survey of variation within and between populations is needed.