Heliotropium 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 : 84-85

2. Heliotropium L. 2

Annual or perennial herbs, sometimes woody at the base. Flowers in terminal or pseudoaxillary, ebracteate and branched cymes. Calyx lobed usually to the base. Corolla hypocrateriform; tube usually without scales; limb lobed more or less to the base, usually with teeth between the lobes. Stamens included. Style included, usually very short; stigma large and disc-like, or conical to subulate, entire or 2- to 4-lobed. Fruit dry, splitting into 4 or 2 nutlets, or 1-seeded and remaining entire. All species grow in dry, open habitats, especially in cultivated ground or sandy soils. Literature: H. Riedl, Ann. Naturh. Mus. (Wien) 69: 81-93

(1966).

1 Flowers long-pedicellate 8. micranthos 1 Flowers ± sessile 2 Plant glabrous 10. curassavicum 2 Plant hairy 3 Perennial; racemes not more than 1 cm, with not more than

8 flowers 9. arguzioides 3 Annual or perennial; racemes more than 1 cm, with more than 8 flowers 4 Perennial; corolla purple 11. amplexicaule 4 Annual; corolla white or cream 5 Calyx lobed to less than | of its length, almost concealing the single-seeded fruit and falling with it 12. supinum 5 Calyx lobed to the base, not concealing the 4 free nutlets,

and persisting after they fall

6 Stems densely villous; corolla with scales in the throat

7. hirsutissimum

6 Stems ±appressed-pubescent; corolla without scales in the throat

7 Corolla 2-5 mm; limb 2-4(-5) mm in diameter

(1-4). europaeum group

7 Corolla 4-7 mm; limb 4-5-8 mm in diameter

8 Stigma filiform, deeply bifid 6. halacsyi

8 Stigma conical, entire or shallowly 2- to 4-lobed

5. suaveolens (1-4). H. europaeum group. Annual; stems 4-40 cm, erect or ascending, usually branched, appressed- to erecto-patent- pubescent. Leaves up to 5-5(-6-5) x 2-8(-3-5) cm, ovate to elliptical, cuneate to almost rounded at the base, rounded to subacute at the apex, appressed-pubescent; petiole up to 3-5 cm. Sepals 1-8-3-5 mm, lanceolate to linear-oblong. Corolla 2-5 mm, at least the limb white; limb 2-4(-5) mm in diameter. Anthers 0-7- 1-5 mm, inserted in middle of corolla-tube. Stigma conical to linear-subulate, deeply or shallowly divided into 2(-4) lobes at apex or rarely entire, glabrous to hairy. Fruit splitting into 4 nutlets, glabrous or pubescent. The species included here are not well understood and some may perhaps not merit specific status. 1 and 4 are usually fairly easily distinguished from each other in the Mediterranean region, but in Russia and S.W. Asia both may be difficult to separate from 2. It might prove more satisfactory to regard 3 as merely a variant of 2 with pubescent fruits, and possibly 2 is only subspecifically distinct from 1. H. stevenianum Andrz. , Enum. Pl. Podol. 116 (1862), described from W. Ukraine, is probably not specifically distinct from 1 but has also been regarded as synony­ mous with 2. In the literature 2 and 4 have been much confused and details of their distribution in E. Europe are uncertain. 1 Stigma linear-subulate, usually glabrous 1. europaeum

1 Stigma conical, usually papillose or hairy

2 Fruit hairy 3. lasiocarpum

2 Fruit glabrous

3 Sepals lanceolate; anthers 1-1-5 mm; stigma usually densely hairy 4. dolosum

3 Sepals oblong or narrowly triangular; anthers 0-7-1 mm; stigma usually papillose 2. ellipticum