About Lettuce Cultivar Groups
A cultivar is a cultivated variety of a plant species.
Where several very similar cultivars exist, these are termed Cultivar Groups.
There are six commonly recognised Cultivar Groups of lettuce which are ordered here by head formation and leaf structure; there are hundreds of cultivars of lettuce selected for leaf shape and colour, as well as extended field and shelf-life, within each of these Cultivar Groups.
Butterhead Lettuce Cultivar Group
Lactuca sativa var. capitata.
Butterhead lettuce, aka Boston or Bibb forms loose heads.
Its leaves have a buttery texture.
Butterhead cultivars are most popular in Europe.
Popular varieties include:
Boston
Bibb
Buttercrunch
Tom Thumb
Chinese Lettuce Cultivar Group
L. sativa var. asparagina.
Chinese Lettuce, also called Asparagus Lettuce, generally have long, sword-shaped, non-head-forming leaves, with a bitter and robust flavour unlike Western types, for use in stir-fried dishes and stews.
Chinese lettuce cultivars are divided into “stem-use” types (called celtuce in English), and “leaf-use” types such as youmaicai (Chinese: 油麥菜; pinyin: yóumàicài) or shengcai (生菜/唐生菜), respectively.
Crisphead Lettuce Cultivar Group
L. sativa.
Crisphead, also called Iceberg, forms tight, dense heads that resemble cabbage.
In the UK and USA, this type is referred to as 'iceberg' lettuce, as it is so crisp and has such a white, crisp, densely packed heart.
Sometimes also known as 'cabbagehead' lettuce.
They are generally the mildest of the lettuces, valued more for their crunchy texture than for flavour.
Crisphead varieties bred specifically for summer growing are slow to bolt.
Their main problem in summer is a slimy internal rotting.
Looseleaf Lettuce Cultivar Group
L. sativa var. crispa.
Looseleaf lettuce has tender, delicate, and mildly flavoured leaves.
This group includes oak leaf and lollo rosso lettuces.
Loose leaf lettuce is a lettuce variety which does not form a compact head.
There are numerous different types of loose leaf lettuce, with basic red and green being the most common.
This lettuce varietal is very easy to grow and it can be flexibly used in a wide variety of recipes, making it a popular choice for the garden and market.
Most markets and greengrocers carry several types of loose leaf lettuce, and it is also possible to grow at home.
Romaine Lettuce Cultivar Group
L. sativa var. romana.
Romaine lettuce, also called Cos, grows in a long head of sturdy leaves with a firm rib down the centre.
Unlike most lettuces, it is tolerant of heat.
The thick ribs, especially on the older outer leaves, should have a milky fluid which gives the romaine the typically fine-bitter herb taste.
Romaine is the usual lettuce used in Caesar salad.
Romaine is the usual lettuce in Middle Eastern cuisine.
Romaine is usually eaten as salad in North America.
Most dictionaries trace the word cos to the name of the Greek island of Cos, from which the lettuce was presumably introduced.
Summer Crisp Lettuce Cultivar Group
L. satvia.
Summer Crisp, also called French Crisp or Batavian, forms moderately dense heads with a crunchy texture.
This type is intermediate between iceberg and looseleaf types.
The outer leaves are thick, crisp and flavoursome, the often conic heart/head is crisp and sweet.
In some varieties, the outer leaves can be harvested as a loose leaf until the head starts to form.
These are quite large lettuces, and need good fertility.
Their particular virtue, apart from their top rate taste, is their ability to 'stand' without bolting.
Lettuce attributes
All things being equal, in hot weather, the Crispheads are the slowest to bolt, then the Summercrisps, the Butterheads, the Looseleaf lettuces and finally the Romaine types. Chinese Lettuce varies depending on the cultivar.
Some lettuces (especially iceberg) have been specifically bred to remove the bitterness from their leaves. These lettuces have high water content and so less "nutritionally dense" than are the more bitter lettuces and those with darker leaves.
While all lettuces contain antioxidants and Vitamin K, romaine and looseleaf lettuce contain five to six times the Vitamin C and five to ten times the Vitamin A of iceberg.
Romaine and butterhead lettuce are good sources of folate.
