Ulex L.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1981, Flora Europaea. Volume 2. Rosaceae to Umbelliferae, Cambridge University Press : 102

24. Ulex L. 1

Very spiny shrubs. Leaves usually alternate, exstipulate, 3- foliolate on seedlings, but on mature plants reduced to scale-like or narrow, usually spine-like phyllodes. Flowers axillary, solitary or in small clusters, sometimes aggregated into racemes or umbellike inflorescences; bracteoles 2, immediately below the flower. Calyx more or less yellow, persistent, divided to the base into 2 lips; upper lip with 2 teeth, the lower with 3 teeth; corolla yellow, persistent; stamens monadelphous. Legume broadly ovoid to linear-oblong, hairy, dehiscent, scarcely exserted from calyx. Seeds 1-6, strophiolate.

Most of the branches may be classified as long or short shoots, though a few are intermediate; the short shoots have usually 2-8 nodes. Primary phyllodes are those borne on long shoots', secondary phyllodes are those borne on short shoots. The part of a short shoot beyond the last node is here called the terminal spine', the lateral branches of the shoot, which may or may not bear nodes, are the lateral spines.

In spite of recent monographic work, the taxonomy of this genus is very imperfectly understood. It seems possible that hydridization is more frequent than has generally been supposed.

Literature: G. Sampaio, Brotéria (Bot.) 21: 142-168 (1924). W. Rothmaler, Bot. Jahrb. 72: 69-116 (1941). C. Vicioso, Revisión del Gènero ‘Ulex’ en Espaha. Madrid. 1962.

1 Bracteoles at least 2 mm wide; calyx with ± patent hairs

1. europaeus 1 Bracteoles not more than 1-5 mm wide; calyx usually with appressed hairs or glabrescent (rarely villous)

2 Most of the secondary phyllodes less than half as long as the lateral spines which they subtend; primary phyllodes not more than 5 mm, narrow, rigid, often glabrous

3 Short shoots and spines with persistent, appressed hairs

7. argenteus 3 Short shoots and spines glabrous, or with crispate or patent hairs

4 All petals exceeding the calyx; calyx 5-6-5 mm 6. micranthus 4 Standard and keel about equalling the calyx; wings shorter; calyx at least 6-5 mm 5. parviflorus 2 Most of the secondary phyllodes more than half as long as the lateral spines which they subtend; primary phyllodes at least

5 mm, ± leaf-like, usually villous

5 Plant pale green; short shoots erecto-patent; phyllodes soft and flexible (W.C. Portugal) 4. densus 5 Plant dark green; short shoots diverging at right angles when mature; phyllodes ±rigid

6 Calyx usually less than 10 mm; standard exceeding calyx by less than 2 mm; petals clear yellow 2. minor 6 Calyx usually at least 10 mm; standard exceeding calyx by 2-5-3-5 mm; petals deep golden-yellow 3. gallii