Mercurialis L. Mercurialis annua, L.

4. Mercurialis L. View in CoL 1

Usually dioecious. Herbs with watery sap. Leaves opposite; stipules small. Male flowers usually in clusters on long axillary spikes; calyx-lobes 3; stamens 8-15. Female flowers solitary or few, axillary, subsessile or pedunculate; calyx-lobes 3; styles 2. Fruit with 2 cells, each with 1 seed.

1 Rhizomatous; aerial stem simple 2 Lower leaves usually scale-like; petiole (3—)5—10(—18) mm 6. perennis 2 Lower leaves like the upper, but smaller; petiole 1-2 mm 7. ovata 1 Not rhizomatous; stems branched 3 Densely tomentose 5. tomentosa 3 Glabrous or sparsely hairy 4 Annual, without a thick woody stock 1. annua 4 Perennial, with a thick woody stock 5 Sparsely hairy; leaves incise-dentate 4. reverchonii 5 Glabrous; leaves crenate-dentate or shallowly sinuatedentate 6 Leaves crenate-dentate; fruit 3-4 x 5-6 mm; seed smooth 2. elliptica 6 Leaves shallowly sinuate-dentate; fruit c. 2x 3 mm; seed rugulose 3. Corsica

1. M. annua L. View in CoL , Sp. Pl. 1035 (1753).

Glabrous or sparsely hairy annual 10-50 cm. Stem branched, often from the base. Leaves 1*5-5 cm, ovate to elliptic-lanceolate, crenate-serrate; petiole 2-15 mm. Rarely monoecious. Female flowers axillary, few, subsessile; calyx-lobes triangular-ovate, acute. Fruit 2-3 x (2-)3-4m m, hispid, rarely nearly glabrous; seed c. 2 mm, ovoid, rugulose. 2« =16, 48, 64, 80, 96, 112. Cultivated ground and waste places. Most o f Europe, but introduced in much o f the north and west. Al Au *Az Be BI *Br Bu Co Cr Cz *Da Ga Ge G r He Ho Hs Hu It Ju Lu Po Rm Rs (C, W, K) Sa Si Tu [FeHbNoSu]. B. Durand, Ann. Sci. Nat. ser. 12 (Bot.), 4: 579-736 (1963), has shown that diploid plants are nearly always dioecious, are widespread, and very variable. Most are completely interfertile, but some saxicolous populations from S.E. France form sterile hybrids with other diploid populations, though some introgres- sion seems to occur. These local diploid populations have been described as M. huetii Hanry , Billotia 1: 21 (1864), and are characterized by small size, long, patent branches, and fruit up to 2 mm wide, ciliate, but not hispid on the surface. The polyploids are characterized by being usually monoecious. Plants with 2« = 48 occur in the coastal regions of Portugal and S. and E. Spain, and also in isolated populations on the eastern coast of Corse, and probably correspond to M. ambigua L. fil , Dec. Prim. Pl. Rar. Hort. Upsal. 15 (1762). The remaining polyploids (2/1 = 64, 80, 96,112) are restricted, as far as is known, to Corse and Sardegna. In the absence of clear-cut morphological characters it does not seem possible to give specific rank to any of the taxa in the complex, though they appear to be distinguishable on the average characters of population-samples.