Originally posted on liseed.org November 2007
Lettuce (Lactuca sativa)
Family: Asteraceae (Sunflower family)
Half Hardy Annual. Sow in the spring, tolerates light frost, transplants well. Bolts first year, produces an easy seed crop. I don''t find a lot of crossing but I'm sure it can.
We always grow a few types of lettuce. I've grown different varieties side by side in hopes that some would just cross but they never do.
Lettuce is in a group of plants called composites, like daisies, sunflowers, zinnias, dandelions and a score of other plants. They produce a flower which technically is actually better called a "head" since it consists of many flowers or florets. Some of those florets can be ray flowers, they are arranged in a concentric way around the outside of the head as a single circle of petals each attached to the ovary or fruit which ripens to contain a single seed. Ray flowers may extend inward from their outer ring to a series of rings which gives the flower head a distinctive doubling effect (double marigolds, for example). Inside there may be disc flowers, often dozens crammed together making up the central part of the head. These little florets don't have the conventional showy petal attached like the ray flowers do but they are attached, each to an ovary which can also mature into a single seeded fruit called an achene. Unless you eat sunflower seeds you probably won't notice that seed of a composite like lettuce is actually contained in a shell-like fruit.
Lettuce flower heads are more like a dandelion than a sunflower and consist of a multitude of densely packed ray florets which open at the same time. As the florets open, the central stigma pushes through a crown of stamens and automatically is pollinated. Therefore, lettuce tends to be self pollinating. In fact, hand crossing lettuces is as tedious as hand crossing peas. There are some very effective insect pollinators that can cross lettuces, I am told. Therefore, you will want to separate varieties by a few meters if you are growing seed crops.
I don't get involved in the stock market but I hear that there are a lot of people out there on Wall Street who are employed to make predictions that this one or that is ready to make great profits for you. Here goes, my prediction is Asparagus Lettuce. I really like the stuff. I never ordered the seed for it from Burpee when they marketed it as Celtuce or Cel-tuce as in "celery lettuce" back in the 1950's, but I've been looking at Asian varieties of vegetables recently and I find that Chinese lettuces are practically all asparagus lettuces. There are many varieties adapted to growing the crop in different seasons. Unlike the direction of lettuce breeding in Europe and America, China bred for a thick, tender stalk. An asparagus lettuce can produce a really massive stalk reaching up to a pound or more. I'm still working on the best techniques of growing this kind of lettuce, but I'm really impressed by it's potential for the restaurant trade. It produces a huge leafy upright bush that likes room to grow. The stem elongates quickly but not to bolt as it continues to produce tender nice salad leaves which you can harvest on an ongoing basis. To harvest the stalk you cut the plant, remove the lower leaves and then lightly scrape the outer epidermis from the stalk which will remove any bitterness. The stalk is sweet, crunchy and tender and the little mass of leaves at the top is very nice on a platter. I've cut the asparagus lettuce small to serve guests, maybe 3 or 4 to the plate with a drizzle of oil and vinegar and boy, do they rave about it. The Chinese lightly stir-fry the stalks in sesame oil until wilted but still crunchy which gives them the more appropriate name, asparagus lettuce.
Vanguard 75, a heading lettuce from USDA-Salinas breeders. Vanguard has been abandoned by the seed industry and is no longer in commerce. Salinas breeders wondered why since it has some very nice qualities for the organic grower. So do we. We agreed to evaluate this lettuce for NOFA-NY as part of the Public Seed Initiative. and found that it has some very nice qualities. It literally roasted in the unusually hot and dry conditions we had this summer, in addition it is growing in our "sand lot", an area where our soils are poor. While it needed drip tape to perform at it's max, it was an easy header, shaping up early and just getting better as the season progressed.
Each lettuce flower head stays open only a day and it will produce seeds like a tiny dandelion with an attached pappus which will allow it to parachute away on the wind. Collecting seed can be an adventure because the lettuce stalk produces many flower heads over a period of many days. When you see the flower heads mature into seed you can go around collecting the seed by bending the stalks into a large paper bag and shaking. Plan to do this daily ritual for a while if you want.
If we aren't worried about losing part of the seed crop (we have enough plants going to seed and it isn't a rare variety), we'll wait for a few days when we see seed formation is going well and then pull the plants out of the ground, loosely slip the upper stalks into a bag and lay the plant in a protected area (the garage or an empty greenhouse) until the seeds mature, additional flowers will continue to go to seed while bagged. Separating the seed from the chaff (fluffy pappus) is done by screening when the flowers are very dry (we leave the flowers in their bags for several weeks) and lose some of their stickiness which can hinder the production of clean seed.