Monday, July 25, 2016

The Weekly Weeder -- Wild lettuce: Ugliest Weed Ever

          Prickly lettuce is one of the ugliest weeds ever when blooming, and it has started to bloom all over town.  As it bolts, its leaves stick out at unnatural angles, edges vertical, showing off its sharp points.  It grows 3-7 feet tall and spreads out at the top into wide, branching panicle of tiny yellow flowers that soon turn to small, fluffy seeds that fly on the wind to other properties.  It grows all over town, particularly on the neglected edges outside fences, and in cracks in the pavements.  It gets its name from the prickles on the base of its stem which pierce the bare hand that tries to pull it.  It screams seediness and neglect.

Young prickly lettuce

This looks like a domestic-wild hybrid of prickly lettuce

          There are many varieties of wild lettuce.  They all have a few traits in common, starting with being a composite flower (many tiny flowers in a each bloom, often with yellow strap petal flowers around the edges of the bloom, but some have all strap petal flowers and others have no petals) with seeds that fly on the wind, much like their short perennial relative, dandelion.  Unlike dandelion, the flowers grow on branching stems that can vary from a few inches to 18” tall in the case of groundsel in the spring, to 6 feet or more in summer with prickly lettuce and cow thistle, which looks much like a thistle with lettuce flowers but is not as spiny as true thistles.  Some wild lettuce mixes with domestic lettuce, creating interesting red shades.

"Soft" wild lettuce

False dandelion, which has been blooming knee-high in yards with dandelion-size flowers, is a wild lettuce.  This year, we have a new tiny, fine variety, half the regular size with half-inch yellow flowers, which has spread widely in the area and pulls rather easily.  We also have a soft, tall-growing variety with very dandelion-like leaves, with long, vertical branches on the stems that easily bend and buckle because the stems are soft and hollow.  Look up wild lettuce varieties on the internet, and you’ll see several more that grow in our woods, at least one of which is actually pretty, but still spreads like a weed.
          Unlike dandelion, they have tap roots usually only a few inches long that do not grow if cut an inch below the top of the root crown, being mostly annual weeds, though false dandelion is perennial and still dies.  They often pull out of the ground easily, but can be cut out if they break off above the crown. 
          If you weed them out of your yard and they keep appearing, there is an infestation within a half-block.  Wind-blown seeds don’t usually fly very far in a city full of trees.
          Also unlike dandelion, these weeds need no summer water to sprout and grow and tend to invade dry lawns, vacant lots, and cracks in pavements.  But they will sprout throughout the year with water as well.  What they need is bare soil or fine-textured mulch to get a touch of sun and hold the water needed to germinate their seeds. 
Whole-leaf mulch dries out on top quickly.  It deprives lettuce seeds in the soil of that touch of sun and those that fall on top of the leaves of the fine-textured seed bed that holds the moisture needed to sprout and grow.  A few layers of soft leaves will stop spring weeds like groundsel before they are eaten by soil life.  A couple inches of harder leaves will stop most weed seeds, and soften the soil to pull the ones that grow, while encouraging big-seeded perennial grasses to take over.  Bigger-seeded annual grasses will also grow through the leaves and need to be weeded out.  They are a softer, lighter green than the perennial grasses; see “cheat” and “foxtails.”

Rycke Brown, Natural Gardener          541-955-9040