Cuscuta 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 : 74-75

1. Cuscuta L. 3

Herbaceous parasites, usually annual. Stems twining, with haustoria. Leaves reduced to minute scales. Inflorescences cymose, spike-like, umbellate or capitulate. Flowers (3-)4- to 5-merous, small, white, yellowish or reddish. Stamens inserted in throat of corolla-tube. Hypostaminal scales attached at base of corolla-tube opposite the stamens. Ovary 2-celled, each cell containing 2 anatropous ovules. Styles free or united. Stigmas capitate or elongate. Fruit a circumscissile capsule dehiscing by an irregular or regular line near base, or remaining closed. Seeds 4 or fewer. Embryo filiform, surrounded by a cartilaginous endosperm. Cotyledons rudimentary or absent.

Inflorescences with capitulate cymes are referred to as glomerules. Mature flowers are essential for identification.

Literature: T. G. Yuncker, Mem. Torrey Bot. Club 18: 113-331 (1932). N. Feinbrun, Israel Jour. Bot. 19: 16-29 (1970).

1 Style 1; mostly parasites of trees and shrubs

2 Style in fruit about as long as stigma; calyx f as long as to equalling corolla-tube 17. monogyna 2 Style in fruit 2-3 times as long as stigma; calyx £-j as long as corolla-tube 16. lupuliformis 1 Styles and stigmas 2 (rarely more); parasites of trees, shrubs and herbs

3 Stigmas capitate

4 Flowersina lax,racemose-paniculateinflorescence; some pedicels at least as long as flowers; capsule globose to ovoid

5 Corolla-lobes deflexed; calyx-lobes ovate, obtuse; corolla detaching from its base at maturity to form a cap to the capsule 4. gronovii 5 Corolla-lobes erect; calyx-lobes triangular-ovate, subacute; corolla persistent at maturity, surrounding the capsule

3. suaveolens 4 Flowersforminga ± compact globoseinflorescence; pedicels usually shorter than flowers; capsule depressed-globose

6 Capsule 2-3 mm in diameter; corolla-lobes triangular, acute; scales abundantly fimbriate, not bifid; flowers 5- merous 2. campestris 6 Capsule 3 -5-4 mm in diameter; corolla-lobes ovate, obtuse or subacute; scales deeply bifid; flowers 4- to 5-merous

1. australis 3 Stigmas elongate

7 Capsuledehiscingirregularly; stigmassubsessile; flowers long-pedicellate, in few-flowered umbel-like glomerules

5. pedicellata 7 Capsuleregularlycircumscissilenearbase; stylesdistinct; flowers mostly sessile or shortly pedicellate, in capitate glomerules

8 Calyx-tubegolden-yellow,shiny andreticulatewhendry; calyx-lobes wide and short, abruptly ending in a short fleshy or long swollen, nearly cylindrical appendage

15. approximata 8 Calyx-tubeneithergolden-yellownorshiny and reticulate; calyx-lobes without a cylindrical appendage

9 Styles (including stigmas) shorter than ovary; glomerules 10-15 mm in diameter; scales not reaching the stamens,

or absent

10 Parasitic on Linum usitatissimum (rarely on other hosts); calyx-lobes acute; stems nearly simple 8. epilinum 10 Parasitic on various species, often on Urtica dioica , rarely on Linum usitatissimum', calyx-lobes obtuse, rarely subacute; stems much branched

11 Flowers 3-4 mm; calyx-lobes obtuse, not longer than tube 6. europaea 11 Flowers 2 - 5 mm; calyx-lobes acute, longer than tube

7. pellucida 9 Styles (including stigmas) longer than ovary, or if as long as ovary or shorter, glomerules 4-7 mm in diameter; scales often reaching the stamens

12 Styles (including stigmas) much longer than ovary; flowers (2-5-)3-4(-5) mm; glomerules 7-10 mm in diameter; calyx-lobes membranous

13 Lobes of calyx and corolla obtuse; pedicels as long as or nearly as long as flowers 11. triumvirati 13 Lobes of calyx and corolla acute to acuminate; flowers sessile or shortly pedicellate 12. epithymum 12 Styles (including stigmas) equalling or only slightly longer than ovary; flowers 1 - 5-2- 5 mm; glomerules 4-6

(-7) mm in diameter; calyx-lobes often ± fleshy

14 Flowers (3-)4-merous; corolla-lobes erect

9. palaestina 14 Flowers (4-)5-merous; corolla-lobes patent

15 Plant blackening when dry; flowers dark purple

10. atrans 15 Plant not blackening when dry; flowers white or purplish

16 Calyx-lobes oblong (rarely ovate), longer than tube, swollen, nearly semicircular in cross-section

14. planiflora 16 Calyx-lobes triangular-ovate, acute, about as long as tube, membranous or somewhat fleshy

17 Styles (including stigmas) shorter than ovary; calyx membranous, usually white 13. brevistyla 17 Styles (including stigmas) as long as or slightly longer than ovary; calyx fleshy, reddish

12. epithymum