Science & Nature • Botany

Romaine lettuce

Romaine lettuce is a type of lettuce in the species *Lactuca sativa*, also known as cos lettuce.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

Romaine lettuce is a type of lettuce in the species *Lactuca sativa*, also known as cos lettuce. It is recognized by its tall, upright heads and crisp leaves, and is widely used in salads, wraps, and sandwiches, most notably in Caesar salad. This leafy Vegetable is a common ingredient in Canadian households.

Description

Romaine lettuce forms elongated, upright heads with narrow leaves and prominent ribs. Leaf colour typically ranges from dark green outer leaves to paler inner leaves, and the texture is crisp.

Nutritional profile

Romaine lettuce is naturally low in calories and sodium while providing vitamins A and K, and also vitamin C, folate, calcium, magnesium, and potassium in smaller amounts.

Uses in food

Romaine lettuce is commonly eaten raw in salads and sandwiches and is widely associated with Caesar salad. Its sturdy leaves also make it suitable for wraps and other fresh preparations.

Names and classification

Romaine lettuce is a lettuce variety within *Lactuca sativa* and is also known as cos lettuce. It belongs to the daisy family, Asteraceae.

Key facts

Romaine lettuce is an upright or heading lettuce with elongated leaves and a firm central rib.
It is also commonly called cos lettuce.
The plant is known for its crisp texture and mild flavour.
Romaine lettuce is low in calories and contains vitamins A, C, and K, along with folate and potassium.
It is a common salad green and the main lettuce used in Caesar salad.

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Canadian context

Romaine lettuce is widely sold in Canadian grocery stores and used in everyday salads and sandwiches; Canadian food and nutrition sources describe it as a familiar leafy green vegetable.

Frequently asked questions

What is romaine lettuce?

Romaine lettuce is a variety of lettuce, scientifically classified within *Lactuca sativa*, known for its tall, upright head and crisp leaves.

Is romaine lettuce the same as cos lettuce?

Yes. Romaine lettuce is also called cos lettuce.

What does romaine lettuce taste like?

It is generally described as mild, crisp, and slightly sweet, sometimes with a slight bitterness.

What nutrients does romaine lettuce contain?

It is low in calories and provides vitamins A and K, with smaller amounts of vitamin C, folate, potassium, calcium, and magnesium.

What is romaine lettuce used for?

It is commonly used in salads, Caesar salad, sandwiches, and wraps.

References

Healthline — https://www.healthline.com/health/food-nutrition/romaine-lettuce
Supports: Common name cos lettuce; nutrient profile; general description.
California Department of Education — https://www.cde.ca.gov/ls/nu/fd/romaine.asp
Supports: Physical description of romaine lettuce leaves and texture.
Lettuce Info — https://lettuceinfo.org/products/romaine/
Supports: Flavor, popularity, and vitamin A and K content.
Precision Nutrition — https://www.precisionnutrition.com/encyclopedia/food/romaine-lettuce
Supports: Cos lettuce name; nutrient profile; flavour description.
Wikipedia — https://en.wikipedia.org/wiki/Romaine_lettuce
Supports: Scientific name and classification details.
University of California, Davis — https://postharvest.ucdavis.edu/produce-facts-sheets/lettuce-romaine
Supports: Upright elongated leaves; use in salads and wraps; romaine/cos lettuce description.
Specialty Produce — https://specialtyproduce.com/produce/Romaine_Lettuce_581.php
Supports: Asteraceae family; cos lettuce name; origin and long cultivation history; varieties and heart form.
USDA Food and Nutrition Service — https://fns-prod.azureedge.us/sites/default/files/resource-files/RomaineLettuce_Fresh.pdf
Supports: Low calories and sodium; vitamins A and K, potassium, folate.