Leucanthemum Mill.
Perennial, rarely annual, herbs. Lvs simple, entire, serrate or 1-2-pinnatisect, alternate. Capitula few in corymbs, or often solitary, terminal, pedunculate; involucral bracts in 2-4 rows, at least the inner with membranous margins. Receptacle flat or convex; scales 0. Outer florets usually ♀, ligulate, and white or pinkish, rarely ⚥ or ♀, tubular, and yellow; inner florets ⚥, tubular. Achenes all similar or somewhat dimorphic, obconic to cylindric or flattened, usually ± evenly 10-ribbed; ribs mostly with mucilaginous cells, and secretory canals between. Pappus a small corona or auricle, sometimes 0.
Key
c. 25 spp., Europe, N. Africa, S.W. Asia. Naturalised spp. 2.
Leucanthemum is part of the Chrysanthemum complex and is said to be distinguished from Chrysanthemum sens. strict. by the homomorphic achenes, with mucilaginous cells and secretory canals. However, the separation of these 2 genera on the basis of achene morphology is not altogether satisfactory, as the ray and disc achenes of L. vulgare, at least, are clearly different, although not as differentiated as in spp. of Chrysanthemum sens. strict.
In Europe there is considerable cytological and morphological variation within the L. vulgare complex and many local or minor variants have been accorded specific rank. Although the complex remains unresolved in Europe, 2 distinct entities can be distinguished clearly in N.Z.; these are treated here as L. vulgare and L. maximum.
