|Plateau Agalinis, endemic to the Edward's Plateau.|
Not much is known about the genus Agalinis, a group of about 70 plant species found in North, Central, and South America. They are partially parasitic or hemiparasitic plants that can make food through photosynthesis, but only after siphoning water and mineral nutrients from a host plant, in this case a variety of different hosts but most typically grasses. They do this by growing haustoria, or a root-like structure that connects their roots to the roots of their host.
Detailed studies of this perplexing genus are few and far between, and little else is known about each species, including who are their pollinators and what are their accurate historical and current geographic distributions. In fact, many species are rare or endemic to a particular area or even federally protected. Of the 34 species in the US, two are found in central Texas, and they are both some of our showiest fall bloomers.
|Prairie Agalinis has a very short stalk attaching it to the stem.|
Prairie Agalinis (Agalinis heterophylla), also called Prairie False-Foxglove, is an erect, airy herb, to 2.5 feet tall, with opposite, simple, narrowly linear leaves to 1.25 inches long. Its 5-lobed, bell-shaped flowers, pink to lavender-tinted white with purple-red spots in the throat, are 0.75 inches long and arise from the stem on 0.1-inch long stalks. It is common in the eastern half of Texas, blooms from September to October, and is found in open floodplains, prairies, stream edges, and creekbanks.
|Plateau Agalinis has a much longer stalk attaching it to the stem.|
Easily confused with Prairie Agalinis is Plateau Agalinis (Agalinis edwardsiana), also called Plateau False-Foxglove and Plateau Gerardia, an uncommon and endemic species found in the grasslands and open woodlands on rocky limestone slopes in about 12 counties on the Edwards Plateau. It can grow to 3 feet tall, with very similar narrow leaves and pink to rose-colored flowers as A. heterophylla, but its flowers arise from the stem on much longer, 1.25-inch stalks. It blooms from September to November, and is a host plant and nectar plant for the Common Buckeye butterfly.
Left alone, both of these species will develop small, spherical capsules that burst open when dry, releasing several tiny seeds that will develop into next year’s plants. These native fall-bloomers are airy, delicate-looking plants that can easily survive dry soils, and bring much needed color to rocky, limestone areas or the edges of our ephemeral creeks and streams. In fact, their genus name comes from the Greek aga- an intensifying prefix meaning ‘large or great’ and New Latin -linis meaning ‘flax’, referring to their superficial, flax-like resemblance. Look for them when the weather begins to cool, and enjoy their attractive, abundant blooms from late summer into fall!