Rain Lilies Appear after Downpour

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By Jake Landers
Published October 2011

Jake Landers Rain Lilies bloom five days after a summer rain in an occasionally mowed park in San Angelo, Texas. Four or five days after a summer rain of an inch or more, expect to see Rain Lilies pop up in lawns, roadsides and parks where the grass has not felt the ultimate manicured care. In some local grassy landscapes there are so many it is hardly possible to take a step without crushing a white flower in full bloom. In less than a week the flowers are gone, replaced by a withering stalk with a 3-parted capsule of jet-black seeds, flat and shaped like the letter “D.” If the rain persists, the seeds may scatter to start a new plant; if not, the seeds are lost, and the mother plant retreats into its underground bulb to await the next summer rain. It’s a good way to survive a drought.

How does it do it? Where are the green leaves that take energy from the sun to replace the energy in the bulb that it took to grow the flower? Is it a parasite that gets its nourishment from its neighbors like the Indian paintbrush? 

Rain Lilies appear by the thousands, shooting up from drought resistant bulbs in Red Arroyo Park in San Angelo, a sight seldom seen in pastures heavily grazed by sheep and goats. If you take your eyes off the flower and look closely at the base of the stem, you will see two or more slender strap-shaped green leaves that emerged a day or so earlier than the flower.  It’s very hard to locate the leaves before the flower stalks appear.

In the brief period of a week the leaves expand from the bulb, make enough food from sunlight to grow the flower and replenish the food in the bulb.  The bulb is the size of a marble and looks like an onion, but it doesn’t smell like an onion, and it is not suitable for eating.  Another name in Spanish is Cebolleta, which means “little onion,” but it still doesn’t make it suitable for eating.

There are several kinds of Rain Lilies in Texas. The most abundant one is Cooperia drummondii, named after two botanists, Daniel Cooper, an Englishman, and Thomas Drummond, a Scottish botanist who had may plants of Texas named in his honor.  Most are white flowered, but one in east Texas is orange.  In all of them the flowers open in the evening and remain open all night, usually lasting only one day, and probably pollinated by a night-flying insect like the moth.

Reading The Landscape

How do you interpret the contrast between the pastures with the abundance of small Mesquite in this photo taken in Concho County, Texas, along Hwy 83?  Click here for my interpretation.


Rain Lilies are readily nibbled by sheep, goats and deer, what little there is for them to nibble.  Their appearance in our pastures is strikingly below what we see in ungrazed  areas, suggesting that Rain Lilies cannot survive if the leaves are grazed off and the bulb does not get a regular replacement of energy it uses up to produce the flowers and leaves.  One in east Texas contributes to a disease in cattle called Photosensitization, in which bare skin and skin covered with white hair are blistered by the sun, becoming weepy, bloody and scabby.  Udders become sensitive, and nursing calves may be kicked off, making for an unhappy situation

When I was a graduate student at Texas A&M in the ’50s, a fellow graduate student was studying the disease, but all he found out was what didn’t cause it.  And he learned how to pronounce the disease “photo-sensi-ti-za-tion.”  Not until a few years ago was the cause of the disease finally discovered by my colleague, Barron Rector, Range Extension Specialist.  It is caused by the deteriorating and decomposing leaves of an east Texas Rain Lily that cows consume unintentionally with each mouthful of grass. To commemorate the discovery, I generated a poem as follows:

It seems silly for a Rain lily to sunburn
a cow, we don’t know how.
Let’s ask Rector the photo-detector.

The moral of this story: Mother Nature has provided us with the beauty of the Rain Lilies of the fields, but in east Texas, at least, she is partial to the Black Angus over anything with white on it. 

Reading the Landscape: Answer

A grazed field of Coastal bermuda lies on the right with Mesquite sprouts from seeds scattered in manure of cattle eating beans from trees along the fences, and shows no mowing for hay in five or so years.  On the left is a mix of Kleingrass and Coastal mowed for hay, no cattle grazing.     —JL

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