Lettuce
Lactuca sativa L.
Order - Asterales
Family - Asteraceae
Names:
Lactuca is from the Latin lac or lactis meaning milk and refers to the milky sap.
Sativa
Lettuce
Other Names:
Summary:
A salad vegetable widely cultivated for its compact crisp head of leaves.
Description:
Cotyledons:
Two.
Leaves:
Form a compact globular head.
Stipules -
Petiole -
Blade -
Stem leaves -
Stems:
Flower stem -
Flower head:
Flowers:
Ovary -
Calyx -
Perianth -
Sepals -
Petals -
Stamens -
Anthers -
Fruit:
Seeds:
Roots:
Taproot.
Key Characters:
Biology:
Life cycle:
Annual. Seed is sown at any time of year. Heads are harvested 6-12 weeks after planting.
Physiology:
Sensitive to frost. Sensitive to high temperatures. Seed stalks form when temperatures are 20-270C
Reproduction:
By seed.
Flowering times:
Seed Biology and Germination:
Vegetative Propagules:
None.
Hybrids:
Allelopathy:
Population Dynamics and Dispersal:
Spread mainly by intentional planting of seed or seedlings.
Origin and History:
Distribution:
ACT, NSW, NT, QLD, SA, TAS, VIC, WA.
Habitats:
Climate:
Cool temperate. Prefers temperatures between 10 and 200C. Cool nights required for good quality. High temperatures lead to bitterness.
Soil:
Well drained with a pH of 6-6.5
Plant Associations:
Significance:
Beneficial:
Detrimental:
Toxicity:
Not recorded as toxic.
Legislation:
None.
Management and Control:
Thresholds:
Eradication strategies:
Herbicide resistance:
Biological Control:
Sensitive to Necrotic Yellows virus which is spread by aphids from Sowthistle to the crop. Lettuce also affected by a seed borne mosaic virus.
Important diseases include Downy Mildew, Grey Mould Rot, Sclerotinia Rot and anthracnose.
Pests include Aphids, Light Brown Apple Moth and Rutherglen Bug.
Related plants:
Prickly Lettuce (Lactuca serriola) is probably the wild parent of Lettuce.
Wild Lettuce (Lactuca saligna) has narrower lobes and no spines on the stem leaves.
Plants of similar appearance:
References:
Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne).
Reid, R.L. (1990) The Manual of Australian Agriculture. (Butterworths, Sydney). P145, 341.
Acknowledgments:
Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.