Species: Lactuca ludoviciana (Nutt.) Riddell

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Lactuca ludoviciana (Nutt.) Riddell

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TAXONOMY

Family:

Asteraceae or Compositae

Genus:

Lactuca

Species Synonyms:

Lactuca campestris Greene
Lactuca campestris var. typica Wieg.

Common Names:

wild lettuce
biannual lettuce
western wild lettuce

DISTRIBUTION

Canada:

southeastern Saskatchewan – southern Manitoba

Saskatchewan:

southeastern Saskatchewan; Antler River Valley

Ecoregion:

Aspen Parkland

HABITAT

Saskatchewan:

low shrublands in river valleys

RARITY STATUS

Provincial Status According
to Harms (2003):

Endangered

Nature Conservancy Status:

G4G5 S1

Saskatchewan Species at
Risk Status:

None

COSEWIC Status:

None

Tall blue lettuce is apparently secure, with numerous populations throughout the province. However, local populations are small, leaving this plant vulnerable to changes in habitat.

SPECIES DESCRIPTION

Height:

1 – 2 m tall

Roots:

taproot

Stems:

to 1 cm wide, solid, hairless, latex brown

Leaves:

basal and lower leaves sessile, 20 – 30 cm long, 5 – 10 cm wide, oval to spoon-shaped, base arrow-like to clasping, hairless, upper midvein short hairy, variously toothed or deeply lobed; middle and upper leaves alternate, clasping with ear-like lobes, 5 – 15 cm long, 3 – 5 cm wide, reduced slightly upwards, oval to spoon-shaped, toothed to lobed, margins sharp but not prickly

Inflorescence:

heads 50 – 100 in loose, branched clusters, to 1 cm across, ray flowers only; bracts ~17, 15 – 23 mm high, overlapping, not black-tipped

Flowers:

ray flowers 20 – 30; 5 – 5.5 mm long, blue, blue with yellow at apex or yellow; anthers white

Fruits:

achenes 4 – 5 mm long, 2 – 3 mm wide, flattened, conspicuous ridge on both sides, dark brown; beak 3 – 4 mm long, thread-like; pappus in 3 – 4 series, white

*KEY TO LACTUCA* IN SASKATCHEWAN**

1 Pappus brown or grey	L biennis
1 Pappus white	2

2 Flowers yellow (may dry purple)	3
2 Flowers purple (may have some yellow)	4

3 Leaves prickly on margin; heads with 6 – 12 flowers; latex white	L. serriola
3 Leaves not prickly on margin; heads with 12 – 20 flowers; latex brown	L. ludoviciana

4 Leaves prickly on margin; latex white (flowers only purplish when dried)	L. serriola
4 Leaves not prickly on margin; latex white or brown	5

5 Plants without a whitish bloom; achenes very flat, median nerve strong, other nerves if present, obscure, beak long and slender; latex brown	L. ludoviciana
5 Plants with whitish bloom; achenes moderately compressed, several prominent nerves, beak short; latex white	L. tartarica var. pulchella