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News Archives September 18, 2007 Herbaceous Plants
Today we discuss the many herbaceous plants that have spines or thorns that we are likely to encounter along the Greenway paths. You have probably come across some of them while weeding your home garden beds. The Smilax genus has two especially wicked plants that can tear the skin when you unexpectedly grab a bunch of weeds. The Sawbrier (S. glauca) is an erect, unbranching plant about 3 to 4 feet high with heart-shaped leaves, pale green on the back, and saw-like teeth along the stem. S. rotundiflora has (obviously, from its name) roundish leaves with stout thorns along the woody vining stems. This is the Common Greenbrier or Catbrier. Bristly Greenbrier (S. tamnoides) has many slender thorns, especially on the stem, near the base of the plant. Greenbrier berries are blue-black or black in small clusters. The common Dewberry, looking like it's relative the blackberry, trails and arches in the undergrowth. It's sometimes mistaken for wild strawberry due to its set of three toothed leaflets. The flowers are white, but when in fruit it resembles the blackberry, and is edible. It's thorns are mainly on the trailing stems. The various Thistles (Cirsium sp) are tall biennials having purple flower heads with swollen prickly bases and the stems and leaves have spiny tips. The first year winter rosette has spiny leaves, too. The Sow Thistles (Sonchus) have dandelion-like leaves, each tooth with a spiny tip. They often twist and wrap around the prickly stem at its base. Their composite flowers are yellow in terminal clusters . Prickly Lettuce (Lactuca scariola) is less fierce looking than the Sow Thistles, but has a similar prickly leaf. Its yellow flowers are smaller and in open branching clusters, growing to 5 feet tall. The six foot Teasel (Dipsacus sylvestris) is often mistaken for a thistle, but actually has small 4-petaled lilac flowers protruding from a pear-shaped floral head. Definitely not a composite. The stiff, horizontal bracts are slender and spiny as well as the stem. The leaves are not spiny. Two Galium species are prickly: Cleavers (G. aparine) stem and whorled leaves have hooked prickles as well as the small fruit, and the Rough Bedstraw (G. asprellum) clings to nearby plants with the aid of its stem prickles. The whorled leaves are only ½ to ¾ “ long. Bedstraw's tiny flowers are in white terminal clusters. Along the Tartan Trail can be found the Common Cocklebur (Xanthium strumarium). This course 3' high plant has ½ - ¾ “ seed burs with short spikes and two hooked beaks at the top. Just sitting ready to catch on to an animal's fur coat and ride along for dispersal elsewhere. Most folks are familiar with the Yucca plant ( Y. filamentosa) with its sword-like leaves. One finds the leaf edge stiff and sharp like a dull knife. The flowers are white on a tall panicle that may reach 6 feet.
The nettles (Laportea) are well known for their reaction on human skin, though in fact not all of them have the stinging hairs that cause the dermetitis. One of the worst is the Wood Nettle ( L. canadensis) with alternate leaves 3-6” long and stinging hairs along the stem. It's tall, to 4' in its favorite places, moist woodlands. Flowers tiny and green on spiny, branched stems. The actual Stinging Nettle (Urtica dioica) is covered with stinging hairs. The leaves are heart shaped, opposite and heavily toothed. Plant to 3' high. The Horse Nettle is in the nightshade family (Solanum). Its prickly stems grow to 4', produce 1” white or violet flowers and the fruit is a yellow berry. So be wary. Don't place your unprotected hands into a overgrown area unless you have looked carefully for any of these prickly plants.
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