Flora of New Zealand Series

yarrow

Strongly scented, rhizomatous herb, with short non-flowering rosettes often forming dense mats. Stems usually erect, sometimes ascending, up to c. 80 cm tall, ribbed and striate, hairy especially above, usually not branched except above to form infl. Basal lvs petiolate, lanceolate, moderately hairy, 2-pinnate with segments again 1-2-pinnatisect, 6-15-(44) × 1-2-(4) cm; primary leaflets in 18-30-(37) pairs; ultimate segments subulate, not all in one plane giving a feathery appearance to lf; rachis c. 1-2 mm diam., flattened, sometimes slightly winged, not toothed. Cauline lvs similar to basal, but above becoming apetiolate, less divided, smaller, and with fewer leaflet pairs. Corymbs usually ± flat-topped or slightly convex, to c. 15 cm across, with numerous, closely packed capitula. Involucral bracts glabrous to sparsely hairy, 1.5-4-(5) mm long; margin brown, hairy. Capitula (3.5)-5-10 mm diam.; ray florets 4-7; ligule and disc florets usually white, sometimes pink to deep red or purple. Achenes grey-brown, c. 2 mm long; wings narrow, pale brown.

N.; S.: throughout, but more common in drier South Id areas; St.: local; K., Ch., A., C.

Europe, Caucasia, Iran, Siberia, Himalaya 1867

Mostly roadsides and waste places, also palustral and coastal sites, pasture, cultivated land, and lawns.

FL (Jun)-Dec-May.

Although the A. millefolium group presents some taxonomic difficulties in Europe and N. America, N.Z. plants are remarkably uniform in most characters and can be referred to the type subsp. There is considerable variation in stature, but this is mostly related to habitat. The fls are usually white, but pale to deep pink forms occur forming small clonal patches within otherwise white-flowered populations. Some small populations may entirely comprise pink-flowered plants. Yarrow is sold as a turf plant, and a selected pink form, cv. 'Cerise Queen' is grown as an ornamental. A few collections (e.g., CHR 324887, Selwyn Huts, Canterbury, Garnock-Jones 1251, 22.7.1979), with deep red-purple ligules and less deeply divided cauline lvs, match descriptions of A. distans Willd. (earlier recorded in N.Z. as A. tanacetifolia). It is most likely that A. distans is not naturalised in N.Z. and these collections simply represent the most extreme forms found within populations of A. millefolium. Deep pink forms have also been recorded in N.Z. as A. rubra.