While Florida's abundant sunshine and rainfall can be a boon to ornamental gardens and agricultural crops, they're also an open invitation to weeds. Weeds, especially the ones that produce attractive blossoms, can catch home gardeners unaware. Several Florida weeds display yellow flowers that can mislead unsuspecting gardeners. Unchecked, these invasive plants will soon crowd out their desirable competition.
Southern Yellow Wood Sorrel
A spreading plant with clover-shaped leaves, southern yellow wood sorrel (Oxalis florida) gets its name from the Greek word for "sour." High oxalic acid content imparts a sour taste to its leaves and binds with calcium, potentially causing a deficiency in any livestock that ingest it. Yellow wood sorrel, says the University of Florida, grows throughout the state.
This annual weed produces mats of leaves and flower stalks with three single yellow blooms. Its oval-shaped light-brown seeds are ridged. Controlling this weed is possible with several commercial lawn herbicides. Choose one that will not adversely affect your type of grass
Bristly starbur (Acanthospermum hispidum), named for its thorns and prickly fruit, is thought to have reached Florida during the 19th century. Well-established in the northern part of the state, it is now invading the south. Starbur spreads when the hooked hairs of its fruit attach to the coats of animals.
This weed is poisonous to goats and mice. Its daisy-like yellow flowers grow on stiff hairy stems, and it begins producing viable seeds when only 9 inches tall. Bristly starbur competes with agricultural crops including peanuts and soybeans, robbing them of nutrients and water. Fortunately, commercial herbicides are capable of controlling up to 80 percent of bristly starbur infestations.
Partridge pea, found throughout Florida, seldom grows more than 12 inches tall. It produces masses of flower clusters--each containing from one to six yellow flowers--in late summer and early autumn. Common wherever the soil has been disturbed, blooming partridge pea is a magnet for sulfur butterflies.
Although considered a weed, partridge pea has found a place in many wildflower gardens because of its abundant blooms and attractive feathery leaves. Bees use it as a honey source, but it has proven toxic to animals when eaten in large quantities.
Partridge pea is an annual, but produces enough seeds to self-sow and return year after year. To use it in a butterfly garden, plant the seeds one-half to three-quarters of an inch deep in full sun between March and May. Partridge pea does best in sandy, dry soil.