What Good Is It?

Part 1 - Habitat Enhancing Land Management

“The last word in ignorance is the man who says, ‘What Good is it?’ If the land as a whole is good, then every part is good, whether we understand it or not. If the biota, in the course of aeons, has built something we like but do not understand, then who but a fool would discard the seemingly useless parts? To keep every cog and wheel is the first precaution of intelligent tinkering.” —Aldo Leopold, 1938

Christine Middleton

In his new book, Lessons from Leopold: Learning from the Land, Steve Nelle highlights Algerita (Mahonia trifoliolata) as an example of what happens when a plant is viewed from just one perspective. He cites an unnamed, well-respected range management specialist who likened Algerita (more commonly known as Agarita) to a wart on the nose. Nelle suggests the range manager was viewing the bush only as something that took up space and was poor feed for livestock. He goes on to state that “a closer examination with an open mind would have revealed considerable seasonal value for deer and songbirds and as a prime nursery shrub to protect other palatable and desirable species.”

These days, a dwindling number of landowners are concerned primarily with forage value. We asked a variety of experts who work with landowners what they hear their clients complain about. We received lots of great input and a variety of reasons certain plants were maligned. Clearly, one major driver of scorn was whether a particular plant caused hurt or annoyance. So Part 1 of this series focuses on plants that are viewed in some way as annoying or injurious. Other plants mentioned as disdained for a variety of other reasons will be the subject of Part 2 in a future article.

Plants that Stick

It’s easy to understand why people find plants that attach themselves to their socks or pets annoying. But have you ever thought about why those plants evolved that way? It’s a method of seed dispersal that enables such species to spread quickly over a wide area. There’s even a word for the transport of seeds on the outside of animals: epizoochory. While such plants seem to be everywhere, only a small percentage of plants spread via epizoochory—estimated to be less than 5%. However, such plants are often the first to populate disturbed areas. As such, they provide ecosystem services like nitrogen fixing and erosion control that are essential to recovery. Also, remember there are other creatures with whom you share your property who value these same plants more than you do.

Let’s start our exploration of plants that disperse via epizoochory with a very sticky plant with an intriguing history. Galium aparine has lots of common names—Stickywilly, Sticky Weed, Catchweed, Cleavers, Goose Grass, and, probably its best known, Bedstraw. Bedstraw is covered with bristles on its stems, leaves, and fruit that cause the plant to stick to both humans and their furry companions. Its pleasant smell and a belief that it repelled fleas were why Medieval Europeans stuffed their mattresses with the plant. It’s unclear whether it is native to Texas or was brought here by early European settlers wanting bug-free places to lay their heads.

Bedstraw
Photo courtesy Christine Middleton

Whether native or not, Texas wildlife have found constructive ways to use Bedstraw. Birds find Galium’s stickiness a great addition to their nest-building efforts. Perhaps they too have found fleas will stay away. One of its other common names, Goose Grass, stems from the fact geese love to feast on its seeds.

The cardinal who built this nest started with Bedstraw as the first layer and used it to hold everything else together. Photo courtesy Cathy Ramsey

Another annoying, sticky plant is Tasajillo (Cylindropuntia leptocaulis). It too goes by lots of common names—Christmas Cactus, Pencil Cactus, Christmas Cholla, Desert Christmas Cactus. Next time one of those annoying segments attaches to your pants, remember: come spring, you will likely see hummingbirds and bees visiting its greenish/yellow/bronze flowers. In winter, those colorful, red tunas provide much-needed nourishment for deer, quail, turkeys, and some songbirds. And it does look awfully pretty dotting a drab winter landscape.

Probably the most hated of native plants are those that produce burs. A bur (also spelled burr) is simply a seed or fruit with hooks or teeth that enable the plant to spread its seeds by attaching to some passing organism, usually a furry animal or clothed human. Another purpose for the hooks is to discourage herbivores who might not want their mouthparts irritated by sharp points. An interesting tidbit is that the bur of a plant (not native to our region) called burdock was the inspiration for the hook-and-loop fastener called Velcro.

Many of the plants people complain about are referred to as sandburs. But that can be confusing because sandbur is part of the common name for lots of species. Many are in the grass genus Cenchrus. Cenchrus spinifex (also referred to as Grass Bur, Coastal Sandbur, Field Sandspur, Southern Sandbur, Spiny Burrgrass) is one of the most common. It will hide in mown lawns and remind us of our thwarted childhood attempts to saunter barefoot. But sandburs have their purpose. Their seeds can be carried for miles and, historically, bison were major carriers. Often such seeds were deposited in the wallows the bison made, providing quick recovery for the bare ground they left behind.

A species with burs not in the grass family, Prairie Sandbur (Krameria lanceolata), also called Trailing Ratany, is also often present in mown grass. Those wine-colored protrusions that make it easy to spot are sepals, not petals. The petals are smaller and tinged with green. Two of these petals produce oil from specialized glands called elaiophores. Some bees in the genus Centris collect this substance using specialized butter-knife/spatula-shaped hairs on their front and middle legs. Thus the popular name “oil digger bees.” What the bees use the oil for is a bit of a mystery. Some species in this genus live in tropical areas, and it is thought they use the oil to waterproof their nests. Another possibility is that the bees mix the oil with pollen to create protein-rich cakes for their offspring.

Perhaps the most universally despised of plants that produce burs is Beggar’s Lice. But again, be careful with the common name. The one we are talking about is Torilis arvensis, also known as Hedge Parsley or Wild Carrot. Unlike the previously mentioned species, Beggar’s Lice is native to Europe, not Texas. However, it is considered minimally invasive, and its flowers are often visited by native pollinators. It is also a food source for the caterpillars of the Black Swallowtail butterfly. Like sandburs, Beggar’s Lice loves bare ground. That’s why it is a good idea to quickly revegetate an area that has been recently disturbed. As native vegetation grows to a height that provides sufficient shade, the Beggar’s Lice will gradually begin to disappear.

A look at burs would not be complete without mentioning another non-native—Bur Clover. Many Bur Clovers are native to the Mediterranean area but are now found virtually around the world. Texas Invasives mentions one species (Medicago minima) which too often inhabits mown lawns. Native American Seed mentions another species (Medicago polymorpha) as an unwanted species in the “Aliens” section of their seed catalog. Interestingly, Native American Seed’s primary objection is not the burs. Rather, the problem is that when those seeds sprout, they form a mat before warm-season native species can germinate. Then summer heat causes the Bur Clover to die back, leaving bare ground. So who likes it? Farmers! A USDA plant guide suggests ways Bur Clover can be used effectively for forage, soil restoration, and weed suppression.

Plants that Cause Discomfort

Sandburs are not the only native species whose natural defenses against herbivory cause humans to dislike them. The word “spinescent” is used to describe plants whose defense mechanisms involve spines, thorns, and/or prickles. Spines are sharp modified leaves, leaf parts, or stipules (i.e., small leaf-like structures that grow at the base of the leaf stalk). Thorns are sharp, modified twigs or branches, and prickles are modified epidermis (i.e., the outermost layer of plant cells). Interestingly, spines, thorns, and prickles can form as a response to herbivory. Fire and pruning can also induce increases in the level of spinescence on a given plant. Age also plays a role, as can drought and heat stress.

Perhaps the most visibly spinescent native is Prickly Pear (Opuntia engelmannii). While cactus spines discourage herbivory, the pads store lots of water. That can be a life-saving water source during periods of drought. In desperate times, wildlife will also eat the pads. And we humans love to order the pads (nopales) at our favorite Mexican restaurant. The spiny pads also provide shelter for birds and small rodents. The fruits of the Prickly Pear called tunas ripen in late summer and feed a variety of wildlife.

Prickly Pear Tunas
Photo courtesy Christine Middleton

These fruits are a critical food source for species like mockingbirds, coyotes, and tortoises, particularly during arid periods when other resources are scarce. Birds are largely responsible for spreading Prickly Pear seeds. That’s why you sometimes see a Prickly Pear growing high up in an oak tree.

In the spring, the nectar-rich flowers are visited by a wide variety of pollinators. And, in a degraded landscape, the roots of the Prickly Pear help to stem erosion.

Prickly Pear Flower
Photo courtesy Christine Middleton

A number of our native trees and shrubs have evolved thorns as protection from herbivory. Two thorny trees, Huisache (Vachellia farnesiana) and Honey Mesquite (Prosopis glandulosa), found mainly in the eastern portion of Hays County, have thorns that can grow up to 2 inches long. Interestingly, when the top of a Huisache is browsed, the thorns on the regrowth are often larger. But much of the disdain for both species is not necessarily related to their thorny existence. Rather, both are too easily spread by cattle who graze on their sweet pods. And both love newly disturbed areas.

But keep in mind their good side. Both fix nitrogen and thus can contribute to more rapid recovery. The wildlife benefits of both species are numerous. Cattle are not the only ones who consume the pods. They are also eaten by birds, deer, and other mammals. The thorny branches provide excellent predator protection and nesting sites for birds and small mammals. Early blooming Huisache, which is also called Sweet Acacia for its fragrant blossoms, is a much-needed nectar source when little else is available. And the honey produced by bees who nectar on Mesquite has a unique flavor prized by many connoisseurs. Mesquite is also the larval host for Heiligbrogt’s Mesquite Moth and the Long-tailed Skipper.

Mesquite Tree
Photo courtesy Christine Middleton

Responsible for many bloody ankles are various species of Smilax (greenbriar). Probably the most common in our area is Saw Greenbrier (Smilax bona-nox). Those sharp points that look like thorns are actually prickles formed from the outermost layer of the stem. But did you know you can add the nutritious tips to your salad? Deer too love to browse the tips that form in spring or after a good rain. The bluish-black berries are eaten by lots of birds, including turkey, quail, dove, and a variety of songbirds. And, like Prickly Pear, a mass of these prickly vines offers shelter from predators.

Saw Greenbriar Berries
Photo courtesy Christine Middleton

White Prickly Poppy (Argemone albiflora) has both prickles and spines. The sharp prickles on its sepals fall off as its showy white flowers expand. But the plant is still protected by spiny leaves. That’s fortunate because White Prickly Poppy is somewhat poisonous. One researcher suggests that the points are so sharp that cattle will not eat it even during severe drought. However, the seeds have a high oil content and thus are an excellent food source for doves, quail, and other birds. According to the Native American Seed catalog: “Birds love the seeds as much as the common sunflower.” And another interesting factoid: during WWII, White Prickly Poppy oil was used as an alternate source for fine lubricant.

White Prickly Poppy Flower
Photo courtesy Christine Middleton

Plants that Cause Allergic Reactions

Certain plants can cause allergic reactions. There’s a quite obvious name for that too—allergenic plants. Not everyone is susceptible to the same plants, but most people are allergic to something. An allergic reaction happens when a person’s immune system regards the plant’s particular pollen or some other substance the plant produces as a threat. In response, their bodies produce chemicals to fight it off. The result—runny nose, watery eyes, coughing, skin eruptions, or other not-so-pleasant reactions. Often the culprit is wind-blown pollen. Wind-pollinating plants tend to produce lightweight grains that float easily. The pollen associated with plants pollinated by insects is usually heavier and stickier, and thus less likely to produce an allergic reaction.

Plants release their pollen at different times of the year. Many among us become miserable in early spring as oaks spread their green pollen everywhere. Other trees that also release allergy-triggering pollens in springtime include hackberry, willows, ash, pecan, and cottonwood. Come winter, Ashe Juniper is the culprit. There’s even a name for that—“cedar fever.”

But who doesn’t appreciate the value of trees, especially in the heat of summer? Did you know oaks and many other tree species host more butterfly and moth caterpillar species than other plants? According to the National Wildlife Federation Native Plant Finder, oaks in our area play host to 468 species of butterflies and moths. And don’t forget about the berries and acorns that provide birds, squirrels, and other wildlife wintertime sustenance. Trees have other significant values too—soil stabilization, carbon sequestration, and aquifer recharge, to name just a few.

When late April comes around, the allergy nemesis is likely grass pollen. But don’t blame native grasses like Little Bluestem. Most of our native grass species are not prolific pollen producers, and so are unlikely to be problematic. Johnsongrass and King Ranch (KR) Bluestem can both trigger allergic reactions. But perhaps the biggest offender is the one planted close to our homes—Bermuda Grass. Just one more good reason to convert our mown lawn to a native mix like Native American Seed’s Thunder Turf.

Come fall, plants often labeled “weeds” are the main trigger for those sneezes and itchy eyes. As the sign at the Lady Bird Johnson Wildflower Center says, don’t blame Goldenrod. Goldenrod blooms at about the same time as Ragweed, which is why it has gotten such a bad rap. There are several species of ragweed in our area. But perhaps the most common are Common Ragweed (Ambrosia artemisiifolia) and Giant Ragweed (Ambrosia trifida). Another source of fall misery is Sumpweed (Iva annua), a relative of ragweed.

Goldenrod
Photo courtesy Christine Middleton

All of these plants are prolific pollen producers. It is said that a single ragweed plant can produce up to one billion pollen grains in a season. But that also means they produce a lot of seeds. Lots of seeds mean the plants can spread rapidly in disturbed areas. However, remember those seeds are exceptionally rich in crude fat and protein and are retained on the plants well into winter. So a great source of sustenance for birds and other animals when other food is scarce. Deer will also browse the tender new growth in early spring.

There are also plants that cause allergic contact dermatitis. How your body reacts depends on a number of factors—the specific plant, how much toxin you come into contact with, and how sensitive your skin is to that particular toxin. The type of reaction can vary from rashes or hives to burns and blisters. These are often accompanied by unpleasant itching or burning.

The most infamous is Poison Ivy (Toxicodendron radicans). What causes the rash is a sticky, pale yellow chemical called urushiol found on all parts of the plants except the surface of undamaged leaves. The oil isn’t a problem unless it is absorbed through the skin and combined with skin proteins, producing a chemical that causes the offending reaction. That means the urushiol must remain on the skin for at least five minutes for the whole process to take place.

Poison Ivy didn’t develop this defense mechanism to annoy us. Scientists think the function evolved as an antimicrobial defense to protect the plants from infection. Most other animals, with the exception of a few other primates, don’t react in the same way we do. But they do appreciate the plant. Squirrels and many birds rely on the red berries when seeds are scarce. The seeds are eaten by quail, turkey, wood ducks, and many species of songbirds as well as small mammals. The leaves provide shelter for small creatures and fair browsing for hungry deer. And, despite the fact that its flowers are small, the blooms are visited by a variety of insect pollinators.

Another plant that invades our epidermis is noseburn. Plants commonly referred to as “noseburn” are in the genus Tragia. What the species in that genus have in common is that the stems, leaves, and fruit are covered with stinging hairs barely visible to the naked eye. But if you turn a leaf sideways to strong sunlight, the hairs will sparkle. That’s because they are tipped with a tiny crystal of calcium oxalate. The crystal enables the plant to pierce the skin, and the pressure releases an irritant under the skin surface.

So why is it called noseburn? Likely because someone saw what happened to sheep or goats grazing close to the ground. Clearly, an effective strategy for a small, low-growing vine to use as a way to deter herbivores. But birds don’t seem to be bothered. The fruit contains three seeds that are consumed by quail, doves, and songbirds with no apparent ill effect.

Want help with your land restoration project? As part of the Hays County Master Naturalist project called HELM (Habitat Enhancing Land Management), we offer property visits to discuss land stewardship. Landowners will learn about sustainable practices to enhance wildlife habitats, improve soil health, manage invasive species effectively, and lots more. If you or your neighbors would like the HELM team to visit, simply fill out the request form at BeautifulHaysCounty.org and help spread the word!

The HELM Network News is a periodic feature in The Hays HUMM, an online magazine of the Hays County Chapter of Texas Master Naturalist™.

The latest issue of the magazine and additional articles you may find of interest can be found at www.BeautifulHaysCounty.org. You can also sign up for our mailing list to receive HELM Network News articles directly in your inbox at BeautifulHaysCounty.org/subscribe-to-helm-news.

Plants that Stick

Plants that Cause Discomfort

Plants that Cause Allergic Reactions

“The Teddy Roosevelt of Texas”