Springtime in Texas is one of the prettiest times of the year because of all the wildflowers that grace the countryside of our state. Bluebonnets are one of the most conspicuous wildflowers and can be seen all over the state. Lupinis texensis, the Texas Bluebonnet, is a member of the Fabaceae or Legume family. It is a cool season plant that spends the winter as a seedling to burst forth and flower as a springtime treat only to set seed and “disappear” until next spring. Bluebonnets are annuals, they complete their life cycle in a year and their offspring return the following year. As a result of mutations, you can see white-flowered and reddish-purple flowered varieties of bluebonnets. Four other species of Lupinis are recognized in Texas.
In the picture above, you can see a small portion of a much larger group of Texas Bluebonnets. These plants taste bad to livestock and consequently are not grazed which helps them cover large areas undisturbed. Our highway department and folks who love bluebonnets scatter their seed which helps this plant to produce large colonies all over the state. Lots of families have pictures of their children in the middle of a stand of bluebonnets. You can visit the Houston Chronicle Website to learn how Texas Bluebonnets became the state flower.
In the picture above, it is possible to see the raceme, or flower stalk of the bluebonnet. Racemes consist of an unbranched stem or shoot from which multiple flowers are suspended by a short flower stalk called a pedicel. Lupinis texensis racemes contain 25 to 40 flowers. Each tiny flower on the raceme has five petals, a centrally located banner petal with a white or purple spot which is flanked by two wing petals. The two remaining petals form the “keel” which is the projection seen below the spot on the banner petal. (look at the flowers on the left side near the top to see this structure). Each tiny flower, or floret as botanists call them, on the raceme grows, opens, and maybe is pollinated before it dies. On the pictured raceme, the oldest flowers are lowest on the raceme. The banner spot on Bluebonnets turn purple with age, the white spots attract the pollinators while the purple spots do not. In this way, Bluebonnets help direct pollinators to fertile flowers of the right age.
Notice the leaves in the image, they are palmately compound and covered with fuzz. Palmate in botanical terms means the leaflets are arranged about a central attachment point like the veins in a palm leaf. Also, the number of leaflets is 5, the same number as petals in the flowers. When all the flowering is done, around May, all that remains of the Bluebonnets are the leafy basal portions of the plant and the remains of the florets that were fertilized which will grow into fuzzy bean pods or legumes containing 3 to 10 seeds for next year’s crop. Such is the life of an annual.