Rare and Unusual Plants

Now that spring is approaching and we have an opportunity to renew our familiarity with the plants that grow here, we picked up on the theme of rare and unusual plants of Central Texas. Sometimes the enjoyment of knowing about plants is to explore the unusual. Sometimes unusual means rare, but not always. There are lots of plants that are very common and at the same time unusual.
Oak trees are not one of our selections of rare and unusual plants, but it would be helpful to spend a minute or so on oaks as they are the unusual of the tree world, in our opinion.
It is estimated that there are 500 oak species in the world and in Texas, we have at least 43 species of the genus Quercus. There are two others that are hybrids. Oaks are unusual because they have a high degree of adaptability to changing habitat. So, the interest in oaks as an unusual plant is in the detail of their genetic structure. How can oaks have this adaptability when, on the other hand, we have a plant that is also unusual, but in stark contrast with the oak. It’s the Texas Wild rice, and it is not adaptable to different environments.
Texas wild-rice (Zizania texana) grows only in the San Marcos River. Those who have walked near the river have seen this grass plant with its long leaves waving in the current of the river. Unless you look carefully, you would not think the leaves could be as long as seven feet.
There are two wild rice plants native to Texas: zizania texana and zizania aquatica. There is a third wild rice native to the USA, but it grows only in the northern wetlands border with Canada. It’s the wild rice that has historically been harvested by the Native Americans for hundreds of years and still is today. It is zizania polustris. All the wild rice grains are long, slender and dark, quite unlike cultivated rice, which is not of this particular rice family. That was the topic in more detail last month.
So, what makes Texas wild- rice special? It’s rare, only growing in the first hundred yards of the San Marcos River after it emerges from Spring Lake. And, secondly, it will only grow in the conditions offered by the first hundred yards of the riverbed.

 Figure 6.1 Texas wild- rice in the river

The conditions necessary are (a) clear water so that sunlight can reach the leaves (b) moving water, so that the leaves get a constant supply of carbon dioxide for absorption into the plant (c) a sandy soil so that the tillers can get a foothold in the soil (d) the avoidance of freezing conditions as the plant is a perennial.
We discussed all these parameters with Chris Hathcock, the Regional Botanist for the US Fish and Wildlife Service located on McCarty Lane in San Marcos. Chris oversees the horticulture of wild rice at the USFW research facility on McCarty Lane where there are large tubs of Texas wild-rice growing in the same conditions that exist in the river. The tubs use the same water as flows from the springs since they pump the water from the Edwards aquifer. Here, at this research facility, they have two purposes. One is to provide a controlled environment to study the plants inability to adapt to other conditions and the other is to maintain a herbarium bank, so to speak, of plants so that in the unlikely event of the destruction of the native stand of plants in the river, they can be replaced from the banked plants.

Figure 6.2 Tubs containing potted Texas wild-rice plants

Figure 6.3 The Herbarium plant bank

Little is known about how Texas wild- rice got into this predicament of having such a narrowly acceptable habitat. But, it will be difficult for this wild rice to get out of this dependency on the specific conditions of the San Marcos River since it is multiplying only by root tillers, which clone the plant. The plant can produce seeds, but the experience of the botanists is that seed production is very low. Perhaps this is because the plant sees no seasonal change except sunlight hours.
For many years, up until 1938, the botanists thought it was the same plant as commonly grows along the gulf coast, the zizania aquatica, but then discovered that texana is different from that aquatica. Aquatica is an annual, it dies each year and new plants grow from seed. Texana is a perennial and it can spread from seed, but mainly from root growth (tillers). Reseeding is probably ineffective in the San Marcos River because by the time the seed picks up enough moisture to germinate and gets washed downriver, it is in unacceptable soil. So, tiller growth seems to be the only way for this plant to spread naturally in this location.
Before the plant was deemed endangered it was viewed as an invasive pest in Spring Lake and the downstream river. It was chopped out, cattle grazed it and so on.
For a time, Texas wild-rice was seen in the Comal Springs water, but that spring dried up in the 1950s so it all perished. The Texas wild-rice is the canary in the coal mine. Take notice if it dies.
The Giant Red Sage (Salvia pentstemonoides) is another interesting plant but does not have the notoriety of Texas wild-rice. This plant, of the salvia family, looks like the common red sage (salvia coccinea) but is much larger and a more elegant plant. This plant needs plenty of water and semi shade, where it likes moist limestone overhangs.

Figure 6.4 Giant Red Sage (Texas Parks and Wildlife)

This plant was known as growing only in Texas, but then for some number of years, it could not be found, and botanists thought it had gone extinct. However, in the late 1980s, it was rediscovered by Marshall Enquist in central Texas. Still, no stands of this plant are known (or let be known) but seeds and plants in nurseries have become available----so reported. An amusing (now) story on the availability of this plant: A few years ago, we were surveying the plants at the plant sale at what is now the city’s Discovery Center and I spotted a very tiny seedling labelled Giant Red Sage. Knowing what I knew about this plant, I bought it, planted it in a spot where it could be kept moist. When it became large enough to identify, I found that I had bought a Mexican Petunia. It shows that many plant sellers do not know their plants as is also the case of the buyer in this instance.
All the literature on this plant says that it is easy to grow in home gardens and has now become widely available. But, a search for the seeds has not been successful. Native Seed of Junction, Texas, for example, reports that their plot of seed producing Giant Red Sage plants was flooded last year and they lost their entire planting.
Stick-Leaf (Mentzelia oligosperma) has been seen by us as a single plant only in our backyard, but it is not considered to be rare, so we are on the lookout for more plants. It is a perennial and a prolific seed maker. The plant is not very tall, it is shrub like in shape and has yellow flowers.
We first discovered it because in whacking it down, we found that the leaves stuck to our shirt sleeves with such a tight grip that only shredding the leaf would remove it and then only partially—even a trip through the washing machine did not remove it all. Surely, the person that held the original patent on the fastening system that became Velcro developed the idea from this plant.

Figure 6.5 Stick Leaf flower and leaves

Figure 6.6 Underside of the leaf of the Stick Leaf

With a microscope, these barbs on the underside of the leaf look like upside down Fir trees.
A look at the range map of this plant shows that it is rather widespread in the midsection of the country----except for its existence in Massachusetts. (may be difficult to see, but Massachusetts is colored green.)

Figure 6.7 Range of Stick Leaf 

In Massachusetts the plant was found growing in a refuse dump of an old wool processing factory. Now, doesn’t that stir your imagination? Some poor old sheep wandered into a patch of Stick-Leaf here in Texas, then went to the shearing pens, the wool was shipped to Massachusetts and cleaned of all the vegetative trash and out went some seeds to the factory dumpsite. Stick-Leaf hiked all the way to the east coast, first to the dock at Galveston, then by boat to Boston and then by wheels to the wool processing plant and then to the processing dump.
This plant also has the common name of Chicken Thief. Again, not holding back your imagination, can you see in your mind’s eye a farmer’s whole flock of chickens being held captive in a patch of these plants? As we would say “might could be true”.
Thurber’s Stemsucker
Most plants grow in the soil, right? Well, not all do, because some are air growing plants like those from the bromeliad family, only using the plant that it grows on as support. Locally we see those plants as ball moss, or, if closer to the coast, a different variety of bromeliad commonly named Spanish Moss. These plants do not grow as parasites by sapping the host plant but use the host plant for support. However, there are some that do live off the host.
But, here is a plant that grows inside the stem of a host plant. Its name is Pilostyles (Pilostyles thurberii) with a common name of Thurber’s Stemsucker. All this plant, except for the flowers, lives inside the stem of the host plant. Its favorite host plant is of the legume family, most notably in Dalea frutensis. It only looks for host plants of the legume family but may chose a different variety of legume depending on where you find it.

Figure 6.8 Pilostyles in bloom by Marshall Enquist

This plant is more common farther to the southwest, but Enquist has found one plant near the headwaters of Barton Creek in Hays County. In the areas of the southwest, the host plant is also a legume, but it is different from frutensis. The parasitic plant apparently does not harm the host plant as Enquist relates that the host plant grew and bloomed normally. The seeds are small, and how they travel to the host plant is unknown.
The Pilostyles plant family (Rafflesia) grows on five continents and consists of ten different species. One of its relatives in Asia puts out a flower that is nearly three feet in diameter, yet its entire plant structure is parasitic living inside the host plant. Plants of this family are unusual in another respect; it has only five or six genes, it does not contain chlorophyll, but transfers some of the genes from the host plant to its own system during the bloom time. It is regarded as one of the most basic of plant organisms and probably has existed for thousands, maybe millions of years.
__________Sightings_____________
Spring is about to spring out on us, so we need to keep our eye out for telltale signs. One such sign well publicized in the past by Leon Hale, is the leafing- out of the mesquite tree. He and a friend used to follow the occurrence of spring from the Rio Grande northward. Those who once lived in Houston might recall his stories in the Houston Chronicle. Leon Hale is getting on in years and does not make this trip to gauge the arrival of spring anymore.
Last year you may recall we had our first blossoming of the Mexican plum tree, but the blossoms then froze, and we ended up with only one plum. Now, right now, the tree is blooming again, and we hope that the last frost has occurred so we can see what this little tree can produce.

Figure 6.10 Mexican plum blossoms.

The hen turkeys are out scouting for nesting places. Here is a photo of one that was wandering through the side yard.

Figure 6.11 Turkey looking for nest site

The flock of turkeys this year seem to be about 20—at least that’s the most we’ve seen at one time this spring.
One last harbinger of spring: the wild redbud in full blossom. There are several of these around, some in Summer Mountain and two in the fence line on Hugo Road.

Figure 6.11 Redbud blooming

R & D TUSCH

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[1] Marshall Enquist’s book on Wildflowers of the Texas Hill Country is probably one of the best plant books to have in your library.