Parietaria L.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1964, Flora Europaea - Volume 1. Lycopodiaceae to Platanaceae, Cambridge University Press : 68

3. Parietaria L. 1

Annual or perennial herbs, sometimes woody at the base, without stinging hairs. Leaves alternate, entire; stipules absent. Flowers hermaphrodite or unisexual, in axillary, bracteate, 3- to many-flowered cymes, one or more in each leaf-axil. Perianth green, cylindrical and 4-toothed in female flowers, 4-partite in hermaphrodite and male flowers. Achenes enclosed in perianth and sometimes in the bracts.

1 Bracts becoming brown, hard and connate, forming a 5-lobed involucre around the achene; leaves rarely more than 1 cm

6. eretica 1 Bracts remaining herbaceous, free or slightly connate at the base; leaves often more than 1 cm

2 Bracts shorter than the perianth in fruit

3 Annual; stem sparsely pubescent; petiole of lower leaves usually equalling or longer than lamina; achenes brown or olive 3. mauritanica 3 Perennial; stem usually densely pubescent; petiole of lower leaves shorter than lamina; achenes black

4 Erect, usually more than 30 cm; leaves 3-12 cm; bracts completely free 1. officinalis 4 Procumbent or ascending, rarely more than 40 cm; leaves not more than 5 cm; bracts shortly connate at base

2. diffusa 2 Bracts equalling or exceeding the perianth in fruit

5 Perianth-lobes incurved and connivent at the apex in fruit; achenes symmetrical at the apex 4. lusitanica 5 Perianth-lobes ± patent and not connivent in fruit; achenes asymmetrically apiculate 5. debilis