Lactuca L.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1976, Flora Europaea. Volume 4. Plantaginaceae to Compositae (and Rubiaceae), Cambridge University Press : 328-329

169. Lactuca L. 3

(inch Scariola F. W. Schmidt )

Annual to perennial herbs. Stem usually solitary, branched. Leaves entire to pinnatifid, often prickly. Capitula few to numerous. Involucre cylindrical; bracts in several rows. Receptacle without scales. Ligules yellow or bluish. Achenes compressed, beaked, usually with ribs; pappus of 2 equal rows of simple hairs.

In the descriptions of achenes, the length includes the beak, and the number of ribs is given for one side.

L. singularis Wilmott , Jour. Bot. (London) 68: 79 (1930) ( L. grosii Pau & Font Quer ), from near the E. end of the Sierra Nevada, S. Spain, is unlike any other European species of Lactuca . It has the stem up to 20 cm, leaves obovate, entire to shallowly dentate, and blue florets. The available material has only unripe achenes which have a short beak; in the absence of ripe achenes the sectional and even the generic position of the species is uncertain.

1 Body of achene darker than beak

2 Ligules blue or lilac; achenes with 1-3 ribs

3 Achenes obovate 16. tenerrima 3 Achenes narrowly elliptical

4 Stem branched from the base; achenes greyish 17. graeca 4 Stem branched only in the upper part; achenes black

15. perennis 2 Ligules yellow; achenes with at least 5 ribs

5 Achenes black or blackish

6 Lateral veins of underside of leaves smooth 13. virosa 6 Lateral veins of underside of leaves spinulose 14. livida 5 Achenes pale

7 Cauline leaves orbicular to broadly lanceolate; inflores­

cence usually a pyramidal panicle

8 Cauline leaves held vertically, spinulose on midrib; involucral bracts patent or deflexed in fruit 9. serriola

8 Cauline leaves not held vertically, smooth on midrib; involucral bracts erect in fruit 10. sativa

7 Cauline leaves oblong to linear; inflorescence usually a spike-like panicle

9 Stem glabrous; achenes subglabrous at apex 11. saligna

9 Stem setose below; achenes setose at apex 12. altaica

1 Body and beak of achene concolorous

10 Ligules blue or bluish

11 Leavesarachnoid-Ianatebeneath; capitulumwithc. 8

florets 7. watsoniana

11 Leavesnotarachnoid-Ianatebeneath;capitulumusually with more than 8 florets

12 Rhizome with underground stolons; at least the middle cauline leaves usually lobed 4. tatarica

12 Rhizome without underground stolons; leaves usually without lobes 5. sibirica

10 Ligulesyellow

13 Stemglandular-hairybelow 8. aurea

13 Stemglabrousor witheglandularhairsbelow

14 Achenes yellowish-brown; stem arachnoid-Ianate at the base 2. acanthifolia

14 Achenes black; stem glabrous or with sparse hairs at the base

15 Leaves not decurrent 6. quercina

15 Leaves decurrent

16 Lower leaves pinnatifid to pinnatisect; undivided part of lamina less than 2 cm wide 1. viminea 16 Lower leaves laciniate-runcinate; undivided part of lamina at least 2 cm wide 3. Iongidentata