Origanum L.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1972, Flora Europaea. Volume 3. Diapensiacea to Myoporaceae, Cambridge: Cambridge University Press : 171

32. Origanum L. 1

Dwarf shrubs or annual, biennial or perennial herbs. Verticillasters few- to many-flowered, aggregated into short, terminal or lateral spicules; spicules arranged in paniculate, cymose or corymbiform inflorescences. Bracts distinct from the leaves, imbricate, often conspicuous, coloured. Calyx campanulate or turbinate, 2-lipped and either actinomorphic with 5 equal teeth, or entire, obliquely truncate at apex, or 1-lipped and deeply slit on one side. Corolla 2-lipped, the upper lip entire or emarginate; lower lip 3-lobed. Stamens didynamous, exserted or included; anther-cells divergent. Style-branches equal.

All species grow mainly in dry places, often on rocky slopes or in dwarf scrub. 1 Calyx 2-lipped

2 Upper lip of calyx entire or subentire

3 Stems densely leafy above; leaves lanate 9. dictamnus 3 Stems ±naked above; leaves sparsely pubescent 10. tournefortii 2 Upper lip of calyx 3-toothed

4 Spicules erect, grouped in panicles at the ends of branches

8. majoricum 4 Spicules nutant, grouped in cymes 5 Caespitose dwarf shrub; leaves less than 5 mm, densely hairy 13. vetteri 5 Rhizomatous perennial; leaves more than 11 mm, glabrous at least above

6 Leaves cordate at base, glabrous or very sparsely scabrid beneath; bracts 7-8 mm wide, glabrous 11. scabnun 6 Leaves rounded at base, sparsely pubescent beneath; bracts 3 mm wide, hairy 12. lirium 1 Calyx either with 5 equal teeth, or truncate and entire at apex,

or 1-lipped and with a deep slit on one side

7 Calyx entire, truncate 7. microphyllum 7 Calyx with 5 equal teeth or 1 -lipped and deeply slit 8 Calyx 1 -lipped, with a deep slit on one side 9 Stems papillose and hirsute; spicules in dense terminal corymbs 6. onites 9 Stems not papillose, glabrous to tomentose; spicules in panicles 5. majorana 8 Calyx with 5 equal teeth 10 Stems usually unbranched; calyx densely covered with purple glands; corolla 8-10 mm 1. compactum 10 Stems branched at least above; calyx sparsely to densely covered with yellowish glands; corolla 4-7 mm

11 Bracts twice as long as calyx, obovate to orbicular, membranous 4. virens 11 Bracts as long as to nearly twice as long as calyx, ovate, herbaceous

12 Bracts 2-3 mm, usually green, densely glandular on outer surface 2. heracleoticum 12 Bracts 4-5 mm, usually purple, eglandular or sparsely glandular on outer surface 3. vulgare