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Tropical Lettuce

The first time I encountered tropical lettuce, or Indian lettuce (Lactuca indica), was when I was exploring a rooftop garden in Fujian province of rural southern China. It was the middle of the day in the middle of the summer, and here was this beautiful lettuce exposed to full sun in a raised bed with less than six inches deep of relatively poor soil. I was amazed that this plant which was obviously in the lettuce genus, was alive at this time of year at all, not even wilting the least bit under the oppressive summer sun in the sub-tropics, and growing with what appeared to be weak care. Needless to say, but my attention had been caught. The plants are shown below:

Tropical Lettuce in China
Tropical lettuce in full sun on a rooftop garden in sub-tropical southern China (Cfa) in summer.

 

Origins

Tropical lettuce is native to southeast Asia, and both India and China have a long history of incorporating tropical lettuce into their agriculture and cuisine. Its native zone is not contained to just the tropics though; the plant is native to very cold temperate Helongjiang in the north, and all the way down to tropical Guangdong in the south.

Researching the current literature on tropical lettuce I discovered discrepancies in its species classification. Lactuca indica is briefly mentioned in Edible Leaves of the Tropics by Franklin W. Martin, and from this source the description and photo of the leaves of the plant matches my own observations, which indicate a tall, erect and heat tolerant lettuce that is bitter in taste. Plants for a Future database has a very similar description as well, although the picture they have of the plant appears similar to a much more wild type of lettuce with a serrated leaf, which is reminiscent of a relatively common weedy species in many places of North America. Adding to the confusion there are Chinese sources that use several different species names. Tropical Lettuce in Chinese is Youmaicai (油麦菜). Looking up the scientific name using that common name will give one the result of Lactuca sativa var. longifolia or Lactuca formosana on various Chinese websites and books, and interestingly the latter is a reference to Taiwan in Portuguese, i.e. Formosa. Oddly enough, this appears to be one of those rare cases that researching with a common name may yield more accurate results than the scientific name.

Growth Habit & Strategies

Tropical Lettuce is a low maintenance biennial that will thrive in gardens with rich soils. The World Vegetable Center, Plants for a Future, ECHO, and the book Oriental Vegetables: The Complete Guide for the Gardening Cook all list tropical lettuce as a perennial. However, in my own observations I have not seen a tropical lettuce plant live more than 2 years.

Like other lettuces, it will grow fine during the cold dry season here in Southwest Florida, and in summers in cool temperate climates. In the subtropical dry season it will grow more vigorously and taller than most veggies common in the garden, as much as 4 feet in height, and can grow up to 8 feet tall in the summer. Where tropical lettuce really shines though is in its ability to tolerate hot summers in tropical climates. It also has the potential to naturalize in sun patches in Agroforestry systems in early succession; a valuable trait generally, but especially in subtropical and tropical gardens. I have recently transplanted some plants into a sun patch in my forest garden and they seem to be thriving with little irrigation. It needs to be kept in check when planted with tender Brassicas however because its growth rate outpaces the latter, or it ought to have its own low maintenance bed devoted to the crop solely on the edge of Zone 1 and 2 (between row crops and agroforestry systems).

Propagation

Seed propagation of the crop is elementary and done easily. In fact, if tropical lettuce goes to seed and disperses naturally via wind it will no doubt pop up in fertile soil in the surrounding area. Once the plant is finished setting seed it can be cut back and will resprout, which is among its many unique virtues. Propagules can also be rooted from cuttings of the mature stems very easily for asexual propagation.

Medicinal and Nutritional information

Tropical Lettuce contains substantial amounts of vitamin A, vitamin B1, vitamin B2, Vitamin C, along with some calcium, iron and other nutrients. The strong flavors of the greens indicate a plant with high nutrient density. Tropical lettuce is also used as a folk medicine for anti-inflammatory, antibacterial, and other medicinal qualities in Asia.

Culinary Suggestions

When eaten fresh, the leaves are more bitter than a traditional lettuce (Lactuca sativa). Tropical lettuce works well in a stirfry or boiled with other greens. The Chinese mainly stirfry it with garlic and a bit of soy sauce as shown in the picture below. It can be eaten as a fresh green balanced with other strong flavored foods and dressings.

Cooked Tropical lettuce

Conclusion

A great choice for the subtopics and tropics, it is also a crop that merits use and experimentation with in many garden contexts, and use in diverse local food systems.Tropical lettuce is a great low maintenance crop that will grow year round in frost free climates, and self sow itself into abundance in the garden. If it starts to spread out too much just dig some out and share it with the community! Try checking out and enjoying the bounty of Tropical lettuce this growing season.

Longevity spinach

Longevity spinach (Gynura procumbens) is a great low maintenance edible medicinal perennial plant to grow in south Florida year round. 

Origins & Climate 

Longevity spinach is a member of the chrysanthemum family (Asteraceae) and is native to West Africa, China, and southeast Asia. It is perennial in Zones 9-11. In any place cooler it should be moved into a greenhouse during winter as sustained below freezing temperatures could kill this tropical plant. 

Growth Habit & Strategies

G. procumbens is a sprawling herbaceous plant with stems that can reach out 20 feet long if left to grow without any maintenance. It is best to give the plant at least 4 square feet of space to sprawl out then maintain the growth that spills out of its designated area by cutting (or eating) the plant back. Some people trellis Longevity spinach; however, I think this requires too much work as the plant needs to be tied to the trellis as it grows. On the other hand, this strategy is useful for those in cooler climates who would need to bring the plant into a greenhouse for the cooler months. G. procumbens sprawls out a bit too much to be used in a densely planted raised bed in my opinion. I believe it is best to incorporate Longevity spinach in an edible perennial landscape and as part of the herbaceous layer in a forest garden. Unlike its cousin Okinawa spinach (Gynura bicolor), which prefers shade, Longevity spinach can grow fine in shade or full sun. G. procumbens prefers rich moist soils and will not perform well in drought conditions. Growth is much faster in the summer months and it slows to crawl throughout the winter. In established plants that are a year or so old can tend to have their old vines, which get covered in new growth, rot out and begin to smell. This is not an issue if the plant is actually eaten and maintained.

Gynura Propagation
These cuttings are well rooted and are ready to be potted up

Propagation

As their are no viable seeds from cultivated G. procumbens the best way to propagate the plant is via cuttingsI like to make a couple 6 to 8 inch cuttings off of an established plant, remove and eat most of the leaves, place the cuttings in a cup of water till they root, then pot them up with a nice soil mix. 

Medicinal and Nutritional information

Several studies suggest that G. procumbens has anti-inflammatory properties and an ability to regulate blood glucose levels along with other medicinal benefits such as lowering cholesterol. In fact, another common name for the plant is Cholesterol spinach. Longevity spinach is used in Southeast Asian folk medicine to treat topical inflammation, rheumatism, and viral ailments. Longevity spinach is also quite high in protein. 

Culinary Suggestions

I prefer to eat the leaves raw; they have a crunchy unique taste that is a bit zesty. When cooked in a stir fry the texture becomes a bit too slimy for my taste. Longevity spinach works great in a soup; the leaves become infused with the spices used and maintain a nice texture. Below is my recipe for Longevity spinach soup. When I give recipes on this blog I"ll seldom mention portions. Whenever I see fine measurements in recipes I always think, "who does this guy think he is telling me how much ginger to put in my soup?"

Longevity spinach soup

  • Cut Longevity spinach leaves 
  • Ginger or Galangal
  • Kombu
  • Shiitake mushrooms
  • Garlic
  • Onions
  • Celery
  • Scallions

Gynura Soup

Considering its high medicinal and nutritional value, Gynura procumbens has an agreeable taste whether cooked or raw; and due to it also being low maintenance​, is a great addition any tropical edible landscape.

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