LACTUCA - LETTUCE

Family: Aster - Sunflower

"Annual to perennial herb; sap milky. Stem: decumbent to erect. Leaf: basal and cauline, alternate, entire to pinnately lobed. Inflorescence: heads liguliflorous, in panicle-like or flat-topped clusters; involucre ± cylindric; phyllaries in 2–several series; receptacle flat or rounded, epaleate. Flower: 6–50+; ligules yellow or cream to blue, readily withering. Fruit: flattened, short- or long-beaked; pappus of 80–120+ bristles, falling separately."
"+/- 100 species: ± worldwide temperate. (Latin: milky) [Strother 2006 FNANM 19:258–263] Lactuca sativa L. (garden lettuce) occasionally escapes from cultivation but does not persist." [Jepson]

"Lactuca is a widely occurring genus consisting of about 75 species (Bremer, 1994) to 100 species (Vries and van Raamsdonk, 1994) mainly distributed in temperate Eurasia [17 species in Europe (Fenikova, 1977)]; some species are also known from southern Africa and North America. Lactuca sativa is the common salad lettuce." [Bohm FSF]


Local Species;

  1. Lactuca biennis - tall blue lettuce [E-flora][PCBC][TSFTK]
  2. Lactuca canadensis - Canadian wild lettuce [E-flora]
  3. Lactuca muralis - Wall Lettuce [E-flora][PCBC]
  4. Lactuca serriola - prickly lettuce [E-flora][PCBC]

Including;

  1. Mulgedium pulchellum - blue lettuce [E-flora][PCBC][TSFTK]
Lactuca biennis
  • General: "Annual or biennial herb from a taproot; stems erect, branched above, usually solitary, glabrous, exuding milky juice when broken, 0.6-2.5 m tall." [IFBC-E-flora]
  • Leaves: "Basal leaves lacking; stem leaves alternate, pinnately cut or toothed, 10-40 cm long, 4-20 cm wide, sometimes hairy along the main veins, the upper ones with ear-like flanges at the base, clasping." [IFBC-E-flora]
  • Flowers: "Heads with strap-shaped flowers, numerous in a narrow, elongate inflorescence; involucres 9-14 mm tall; involucral bracts lanceolate, graduated, often purplish at the tip, glabrous; ray flowers bluish to white, sometimes yellow, 13-34." [IFBC-E-flora]
  • Fruits: "Achenes thin-edged, prominently nerved, beakless or shortly stout-beaked less than 1/2 the length of the body, 4-5.5 mm long; pappus brownish." [IFBC-E-flora]
Lactuca canadensis
  • General: "Annual or biennial herb from a taproot; stems erect, branched above, usually solitary, glabrous or sometimes coarsely stiff-hairy, exuding milky juice when broken, 0.3-2.5 m tall." [IFBC-E-flora]
  • Leaves: "Basal leaves lacking; stem leaves alternate, entire or toothed to pinnate, 10-35 cm long, 1.5-12 cm wide, triangular-shaped or narrowed at the base." [IFBC-E-flora]
  • Flowers: "Heads with strap-shaped flowers, numerous in a narrow, elongate inflorescence; involucres 10-15 mm tall; involucral bracts lanceolate, graduated in 4-5 series, often purplish at the tip, glabrous; ray flowers yellow, 13-22." [IFBC-E-flora]
  • Fruits: "Achenes blackish, flat, median nerve on each face, 4.5-6.5 mm long including the slender beak which varies from 1/2 as long to as long as the body; pappus white." [IFBC-E-flora]
Lactuca serriola
  • General: "Biennial or winter annual herb from a fibrous root; stems erect, branched above, solitary, glabrous, exuding milky juice when broken, 0.3-1.5 m tall." [IFBC-E-flora]
  • Leaves: "Basal leaves lacking; stem leaves alternate, prickly on the underside midrib, finely so on the margins, pinnately lobed or sometimes lobeless, twisted at the base to lie in a vertical plane, arrow-shaped, clasping, mostly 5-30 cm long, 1-10 cm wide." [IFBC-E-flora]
  • Flowers: "Heads with strap-shaped flowers, numerous in a rounded inflorescence; involucres 10-16 mm tall; involucral bracts linear-lanceolate, irregularly graduated in 4 series; ray flowers yellow, often drying to blue, 13-47." [IFBC-E-flora]
  • Fruits: "Achenes prominently nerved, grey or yellowish, 6-7 mm long with the slender beak 1-2 times as long as the body, compressed; pappus whitish." [IFBC-E-flora]
Lactuca muralis (Mycelis muralis)
  • General: "Annual or biennial herb from a fibrous root; stems erect, branched above, solitary or more usually several, glabrous, often glaucous, exuding milky juice when broken, 30-90 cm tall." [IFBC-E-flora]
  • Leaves: "Basal leaves lacking; stem leaves alternate; basal and lower leaves 6-18 cm long, 3-8 cm wide, pinnately cut with a broad, ivylike terminal segment, the bases with earlike and clasping flanges, glabrous, middle and upper leaves few and reduced." [IFBC-E-flora]
  • Flowers: "Heads with strap-shaped flowers, numerous in a rounded inflorescence; involucres 9-11 mm tall; involucral bracts in 2 series, the outer lanceolate, the inner much reduced, linear, glabrous or nearly so; ray flowers yellow, 5." [IFBC-E-flora]
  • Fruits: "Achenes several-nerved, approximately 4 mm long including the 1 mm long beak; pappus white." [IFBC-E-flora]
Mulgedium pulchellum
  • General: "Perennial herb from extensive rhizomes; stems erect, branched above, solitary, glabrous or glaucous, 0.2-1.2 m tall." [IFBC-E-flora]
  • Leaves: "Basal leaves lacking; stem leaves alternate, linear to lanceolate or oblong, the lower ones 5-14 cm long, 6-35 mm wide, entire or more or less pinnately cut, rarely sharply toothed, stalked, the upper ones reduced, becoming entire, unstalked to somewhat clasping." [IFBC-E-flora]
  • Flowers: "Heads with strap-shaped flowers, several to numerous in an elongate to rounded inflorescence; involucres 15-20 mm tall; involucral bracts narrowly egg-shaped, graduated, the outer shorter, often purplish; ray flowers blue or sometimes violet to blue, 18-50." [IFBC-E-flora]
  • Fruits: "Achenes oblong-lanceolate, short-beaked, the beak equaling or less than 1/2 the length of the body, compressed, several-nerved on each face, glabrous, 6-7 mm long including the prominent beak, pale brown; pappus white." [IFBC-E-flora]

Habitat/Range:
"Moist ditches, meadows and forest openings in the lowland, steppe and montane zones; frequent throughout most of BC; E to NF and S to NC, CO and CA." [IFBC-E-flora]
Damp thickets. Eastern N. America [PFAF]

Status: Native[E-flora]

Habitat/Range:
"Mesic to dry roadsides, fields and waste places in the lowland, steppe and montane zones; infrequent in extreme S BC; introduced from E North America." [IFBC-E-flora]

Status: Exotic.[E-flora]

Habitat/Range:
"Dry roadsides, fields and waste places in the lowland, steppe and montane zones; common throughout S BC; introduced from Europe." [IFBC-E-flora]

Status: Exotic.[E-flora]

Habitat/Range:
"Moist to mesic forests in the lowland and montane zones; common in S BC, also in Queen Charlotte Islands; introduced from Europe." [IFBC-E-flora]

Status: Exotic [E-flora]

Habitat/Range:
"Moist to mesic meadows and shrublands in the steppe and montane zones; frequent throughout all but NW and SW BC; N to AK, YT and NT, E to ON, MN and MO and S to OR and CA." [IFBC-E-flora]

Status: Native [E-flora]


Food Use

Medicinal Use

Cultivation

Allelopathic Constraints:

"Cyanogenins had a mainly inhibiting effect on seed germination of Lactuca sativa (lettuce)" [EMNMPV.1]

"All five guaianolides, annuolides A–E, from sunflower leaves, possessed potential allelopathic activity, in particular over dicotyledon species when tested for their effects on the germination and growth of the dicotyledon Lactuca sativa" [EMNMPV.7]


Lactuca virosa - Wild Lettuce (No reports of this species on Vancouver Island)

Hazards

Food Use

Medicinal Use

Phytochemicals


Tall Blue Lettuce - Lactuca biennis

Family: (Aster family) [E-flora]

"The flowers are hermaphrodite (have both male and female organs)
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: acid, neutral and basic (alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil." [PFAF]


Medicinal Uses


Synonyms


Canadian Wild Lettuce - Lactuca canadensis

Family: (Aster family) [E-flora]

Synonyms

Identification

"Lactuca canadensis is a BIENNIAL growing to 3 m (9ft 10in). It is in flower from Jul to September, and the seeds ripen from Aug to October. The flowers are hermaphrodite (have both male and female organs) and are pollinated by Insects.
Suitable for: light (sandy) and medium (loamy) soils and prefers well-drained soil. Suitable pH: acid, neutral and basic (alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil." [PFAF]

Habitat/Range

"Thickets, woodland borders and clearings[43]. Moist open places[235]. Usually found in sandy soils[274]. Eastern N. America - Nova Scotia to British Columbia, south to Georgia and Colorado." [PFAF]


Hazards


Food Use

Medicinal Uses

"The whole plant is rich in a milky sap that flows freely from any wounds. This hardens and dries when in contact with the air[4]." [PFAF]


Nutritional Information

Greens (per 100g fresh weight) [Turner&Kuhnlein]

85g water
2.6g protein
0.8g fat
1.8g crude fiber
0.40mg Riboflavin

131 Vit A RE
337mg calcium
67mg phosphorus
747mg Potassium

Cultivation & Propagation


Wall Lettuce - Lactuca muralis

Family: (Aster family) [E-flora]

Synonyms

Identification

"Mycelis muralis is a PERENNIAL growing to 1 m (3ft 3in). It is in flower from Jul to September. The flowers are hermaphrodite (have both male and female organs) and are pollinated by Bees, flies, self.The plant is self-fertile.
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: acid, neutral and basic (alkaline) soils and can grow in very alkaline soils. It can grow in full shade (deep woodland) or semi-shade (light woodland). It prefers dry or moist soil." [PFAF]

Habitat/Range:" Walls, rocks etc[5], and sometimes in beech woods, usually on base-rich soils[17]. Europe, including Britain, from Scandanavia south and east to N. Africa, the Caucasus and W. Asia." [PFAF]

Ecological Indicator Information
" A shade-tolerant/intolerant, submontane to montane, European forb introduced to Pacific, Cordilleran, and Atlantic North America. Occurs in maritime to submaritime cool mesothermal climates on fresh to moist, nitrogen-rich soils; its occurrence decreases with increasing elevation and continentality. Frequent in semi-open, seral forests on disturbed water-shedding and water-receiving sites; common, occasionally dominant, in early-seral communities on cutover and burnt site (often inhabits exposed mineral soil). Often grows with Achlys triphylla, Epilobium angustifolium, Kindbergia oregana, Polystichum munitum, and Tiarella trifoliata. A nitrophytic species characteristic of Moder and Mull humus forms." [IPCBC][E-flora]


Food Use


Prickly Lettuce - Lactuca serriola

Family: (Aster family) [E-flora]

Identification

"Lactuca serriola is a BIENNIAL growing to 1.5 m (5ft) by 0.3 m (1ft in).
It is hardy to zone (UK) 7. It is in flower from Jul to September, and the seeds ripen from Aug to September. The flowers are hermaphrodite (have both male and female organs) and are pollinated by Self.The plant is self-fertile.
Suitable for: light (sandy) and medium (loamy) soils and prefers well-drained soil. Suitable pH: acid, neutral and basic (alkaline) soils. It cannot grow in the shade. It prefers moist soil." [PFAF]

Habitat/Range
"Waste places, walls, occasionally on more or less stable dunes[17]. S. and C. Europe, incl Britain, from the Netherlands south and east to N. Africa and the Himalayas." [PFAF] " Prickly lettuce is generally more common than great lettuce [L. virosa]." [BackMed]

Synonyms
Lactuca scariola [E-flora][PFAF]
L. serriola = L. scariola = L. integrata.[Harrington]


Hazards


Edible Uses

"Our modem-day common lettuces (L. sativa) are believed to be a cultigen evolved from prickly lettuce. The resemblance is still somewhat apparent in very young prickly lettuce leaves, both in texture and in flavor. The youngest leaves are good in salads, but the older leaves become extremely bitter, in some cases requiring a few boilings to render them palatable." [Nyerges]
"Prickly lettuce has become one of my staples because of its ready availability in vacant lots around here. I usually steam. it with a wide variety of wild and domestic greens. Some tender leaves can even be found now [written August 17, 1980] on young plants as the plant seems to reseed even during these dry hot months." [Nyerges]

Other Uses

Medicinal Uses


Phytochemicals

Chemical Constituents of Lactuca scariola - Prickly Lettuce [DukePhyt]
  • 8-DEOXYLACTUCIN Plant DUKE1992A
  • ALPHA-TOCOPHEROL Seed DUKE1992A
  • ARACHIDIC-ACID Seed 1091 DUKE1992A
  • BETA-AMYRIN Plant DUKE1992A
  • BETA-LACTUCEROL Latex Exudate DUKE1992A
  • BETA-SITOSTEROL Seed DUKE1992A
  • CAOUTCHOUC Latex Exudate DUKE1992A
  • CAPROIC-ACID Seed 7392 DUKE1992A
  • CITRIC-ACID Latex Exudate DUKE1992A
  • FAT Seed 352000 DUKE1992A
  • GAMMA-LACTUCEROL Latex Exudate DUKE1992A
  • GERMANICOL Plant DUKE1992A
  • HYOSCYAMINE Latex Exudate DUKE1992A (This report has been discredited by at least one source)
  • INULIN Root DUKE1992A
  • LACTUCIN Latex Exudate DUKE1992A
  • LACTUCOPICRIN Plant DUKE1992A
  • LINOLEIC-ACID Seed 165616 204160 DUKE1992A
  • MALIC-ACID Latex Exudate DUKE1992A
  • MANNITOL Latex Exudate DUKE1992A
  • OLEIC-ACID Seed 95040 130170 DUKE1992A
  • OXALIC-ACID Latex Exudate DUKE1992A
  • PALMITIC-ACID Leaf 14080 52800 DUKE1992A
  • RESIN Latex Exudate DUKE1992A
  • SQUALENE Seed DUKE1992A
  • STEARIC-ACID Seed 13165 DUKE1992A
  • TARAXASTEROL Latex Exudate DUKE1992A

Nutritional Information

Greens: (Per 100g fresh weight)[Turner&Kuhnlein]
31 kcal energy
2g protein
41mg Vit. C


Cultivation & Propagation

"Prefers a light sandy loam in a sunny position[1, 13]. The wild lettuce is cultivated for the oil in its seed in Egypt[46, 61]. A compass plant, the top leaves align north-south[200]." [PFAF]
This annual or biennial puts forth its new growth in the spring and flowers in the summer and fall. [Nyerges]

Seed - sow spring in situ and only just cover the seed. Germination is usually fairly quick.[PFAF]


Blue Lettuce - Lactuca pulchella

Family: (Aster family) [E-flora]

Identification

"Lactuca pulchella is a PERENNIAL growing to 1 m (3ft 3in). The flowers are hermaphrodite (have both male and female organs) and are pollinated by Insects.
Suitable for: light (sandy) and medium (loamy) soils and prefers well-drained soil. Suitable pH: acid, neutral and basic (alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil." [PFAF]

Synonyms

Habitat/Range
"Medium-dry to moist soils in fields, thickets of prairies, valleys and in mountains to 2,100 metres[212]. Range N. America - Alaska to Minnesota, south to Missouri, New Mexico and California."[PFAF]


Hazards

Caution: "Although no specific mention of toxicity has been seen for this species, many plants in this genus contain a narcotic principle, this is at its most concentrated when the plant begins to flower. This principle has been almost bred out of the cultivated forms of lettuce but is produced when the plant starts to go to seed[13]." [PFAF]


Edible Uses

Medicinal Uses


Cultivation & Propagation


References

Journals of Interest