Search Nature Watch

Friday, October 2, 2020

False Foxgloves


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.

Common Buckeye

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!

Tuesday, July 28, 2020

A Killer of a Wasp

In late June and July, cicadas begin emerging from the ground,
breaking  through their shells or exuviae,
leaving the empty husks behind.

What are those large, solitary wasps we see flying around our yards from late June to September?  Often referred to as the Cicada Killer or Cicada Wasp (Sphecius speciosus), this native species occurs in the eastern and midwestern U.S. regions, southwards through Texas into Mexico and Central America. Cicada killers are so named since they prey on cicadas and provision their nests with them.  While large and intimidating, they offer a measure of natural control on cicada populations.  They benefit our native plants by pollinating flowers and protecting trees from the numerous cicadas that feed on their roots and foliage.

Cicada Killer or Cicada Wasp nectaring at a flower.

Cicada killers are robust wasps up to 2 inches long, with amber wings and black to reddish-brown abdomens with yellow stripes.  The females are somewhat larger than the males, and both are among the largest wasps in the U.S. These solitary wasps have a very unusual and interesting lifecycle.  Females are commonly seen skimming around areas with sparse vegetation for nesting sites, burrowing a tunnel, 10 to 20 inches deep, in dry or bare soil.  In digging a burrow, she will dislodge the soil with her jaws, and using her hind legs that are equipped with special spines, push the loose soil behind her as she backs out of the burrow. 

Cicadas, like this Megatibicen resh,
are hunted by the female Cicada Killers.

The female cicada killer proceeds to capture cicadas, sometimes even in flight, paralyzing them with her venomous sting.  She places the cicadas beneath her, grasping them with her legs, and either flies or drags her prey, which is twice her weight, into her burrow.  After placing a few cicadas in her nest, she begins to lay her eggs.  Females can predetermine the sex of the egg, and she lays multiple male eggs on a single cicada.  But each female egg is given 2 or 3 cicadas, as females are larger, require more food, and more females are needed to create new generations.  Eggs are always laid under the left or right second leg of the cicada. The female then closes the burrow with dirt, as the eggs hatch in a few days, but the larvae take some time to mature, feeding on cicadas as they overwinter in their burrow, not emerging as adults until the following spring.

Adult male cicada killers emerge in spring before the females, defending the territory around their emergence hole and searching for females.  They typically perch on the ground, flying up to attack any rival males. Once females emerge, mating occurs, and the males die shortly after.  Females live long enough to dig and provision their nests, and die after laying all of their eggs.

Cicada killer wasps are not aggressive toward humans and rarely sting unless provoked by grasping them roughly, accidentally stepping on them, or if caught in clothing.  Only the females have stingers, and while males will actively defend their perching areas against other males near nesting sites, they have no stingers. Both males and females have large jaws, but they are not known to grasp human skin and bite.  If swatted at, they will just fly away rather than attack. They are simply focused on cicadas or other cicada killers!

Tuesday, June 16, 2020

Evening Chorus

Green Tree Frog
From late winter into early summer, many of the night sounds you hear are not insects at all, but members of a wide-ranging group of cricket, tree, chorus, and chirping  frogs.  This group of frogs and their allies have adaptations that reveal their mostly arboreal lifestyle, such as forward-facing eyes for binocular-like vision, adhesive pads on their fingers and toes, and a fondness for eating insects.  Often not seen due to their diminutive size, these frogs are commonly mistaken for insects, due to their ability to produce loud and varied mating calls.  Known as ‘advertisement calls’, these calls are produced by the males to attract females and warn other rival males during the breeding season.

Blanchard's Cricket Frog
At ½ to 1 ½ inches, Blanchard’s Cricket Frog (Acris crepitans blanchardi) is found throughout most of the state, except for the Panhandle and West Texas.  Gray to green-brown, this frog has a long rounded snout, dark bands behind its limbs, and a distinguishing triangular patch behind the eyes that points down its back. Diurnal and active all year, these frogs prefer shallow but permanent ponds with vegetation and full sun.  Often seen basking during the daytime, they will jump quickly into the water or away when disturbed, and are capable of covering 6 feet in one leap!  Although they are part of the tree frog family, they are much more terrestrial and are excellent swimmers.  When chorusing, especially at night, the male’s call sounds like clicking small rocks or pebbles together.  Mating occurs in late spring, with the female laying one egg at a time on submerged vegetation.

Green Tree Frog
The Green Tree Frog (Hyla cinerea) is a common, 1 to 2 inch frog with a slender, bright green body, cream-colored belly, and white lips that extend into lateral stripes along the sides of its body.  Found in the eastern third of our state, this frog walks rather than jumps when on the ground.  It is nocturnal, and prefers wet areas such as swamps, edges of lakes, and stream sides.  During its breeding season from March to October, the males start calling just before dark, and sound like groups of tiny ducks quacking.   Females, which are slightly larger than the males and lack the wrinkled vocal pouch, lay their fertilized eggs enclosed in a jelly envelope attached to floating vegetation.   Influenced by the weather, breeding often takes place during or after a rain.

Cliff Chirping Frog
At ¾ to 1 ½ inches, the nocturnal Cliff Chirping Frog (Syrrhophus marnockii) is found in the cracks and crevices of limestone cliffs.  Mostly green with brown mottling and dark crossbars on its hind limbs, this frog also has a proportionately large head and big eyes.  It can run, leap, and hop, and its flattened body allows it to slip into cracks in the rocks to avoid predators.  Sounding a bit like a shy cricket, the call of the Cliff Chirping Frog is a series of short, clear chirps and trills.  While calls are made throughout the year, they are sharper and clearer when females are present.  From February to December females may lay eggs as many as three times in moist leaf litter or soil, although peak breeding occurs in April and May.  

When you’re out at night from winter to late spring or early summer and near one of our natural areas, sit quietly and in no time you should be able to identify the unmistakable sounds that make up the evening chorus!

Friday, May 15, 2020

Quercus with a Purpose

All oaks, like this Post Oak, are members of the genus Quercus.
Texas is home to dozens of native species of oaks, all of which are in the genus Quercus.  These trees provide humans with ample shade in the summer and beautiful color in the fall, and they sustain many mammals and birds with their acorn fruit.  But did you know that they are native host plants for dozens of butterflies and moth species, or the plants the female adults lay their eggs on for their caterpillars to eat?  In turn, the caterpillars of these butterfly and moth species provide a critical food source for almost all of the songbirds raising broods in the spring. Three of the most productive native oak species in central Texas are the Texas Live Oak (Quercus fusiformis), Post Oak (Quercus stellata), and Bur Oak (Quercus macrocarpa).

Texas Live Oak
The Texas Live Oak is also known as Escarpment Live Oak, Hill Country, and Plateau Live Oak.  Considered a semi-evergreen tree, the previous year’s leaves fall from the tree only when pushed out by newly emerging ones in early spring.  It has a stately mature form and unparalleled longevity, reaching to 40 feet in height with large limbs that over time spread an appreciable distance from the main trunk.  Firm textured leaves are oval to elliptical, 1 to 3 inches long, with young leaves having pointed lobes.  Its acorns are spindle-shaped or fusiform, narrowed at the base and ¾ to 1 inch long.  

Juvenal's Duskywing
Grote's Buckmoth
The Texas Live Oak is a host plant for Oak Hairstreak (Northern form), Juvenal’s Duskywing, and Meridian Duskywing butterflies, as well as Grote’s Buckmoth, Eastern Buckmoth, and Delilah Underwing moths.

Post Oak
Also known Iron Oak and Cross Oak, Post Oak is a deciduous oak to 50 feet, coarsely-branched with a dense, oval crown.  Its leaves are typically 3 to 5 inches long, with 4 pairs of lobes on each side, and the upper pair are often larger than the others, resembling a cross.  Acorns are ¾ to 1.25 inches long.  Post Oak is the most common oak throughout Texas, and its hard or iron wood is used for railroad ties as well as construction posts and timbers.  

'Northern' Oak Hairstreak
Polyphemus Moth
It is a host plant for the Oak Hairstreak (Northern form) and White M Hairstreak butterflies, and the Polyphemus, Eastern Buckmoth, Scarlet Underwing, and Little Nymph Underwing moths.

Bur Oak Acorn
Bur Oak is one of our largest oaks, also known as Savanna Oak, Overcup Oak, Prairie Oak, and Mossy-cup Oak.  A deciduous tree that can exceed 100 feet in height, its massive trunk supports heavy, horizontal limbs and lobed leaves up to 9 inches long.  Its acorns are the largest of all native oaks, up to 1.5 inches wide, with much of the acorn enclosed in a coarsely scaled cup with a heavily fringed margin. Sometimes spelled Burr Oak, it is the northern most oak in the New World, extending farther north than any other oak species.  

Banded Hairstreak 
Imperial Moth
Bur Oak is the host plant for the Banded Hairstreak and Juvenal’s Duskywing butterflies, in addition to the Ilia Underwing, Imperial, and Greater Oak Dagger moths.

While Texas is known for its oaks, care must be taken in identifying and maintaining oak trees.  Most all of the species can hybridize, occasionally making exact identification difficult,  and several of them are susceptible to oak wilt disease. However, they are worth the effort from a human and wildlife standpoint, as they are Quercus with a purpose!

Sunday, April 5, 2020

Blue Beauties

Blue Curls, Phacelia congesta
Spring brings a festival of color to our landscape in the form of wildflowers, mostly in shades of red, yellow, orange, purple, pink, and white.  But the most infrequent color of them all is blue.  There is no true blue pigment in plants, so they don’t have a direct way to produce blue color.  Plants have to perform a sort of trickery to produce blue blooms, using a common plant pigment called anthocyanin.  Plants have evolved to tweak their normally red to purple anthocyanin pigments by naturally modifying pH and then mixing those pigments, and combined with the way natural light reflects, these factors result in the creation of blue flowers.

Dayflower, Commelina erecta
Aside from the well-known bluebonnet, there are other blue beauties in bloom this time of year, including Dayflower (Commelina erecta), Blue Curls (Phacelia congesta), and Texas Bluestar (Amsonia ciliata).  Dayflower is a 3-foot high perennial with soft jointed stems that grow upright only if supported by other plants.  It blooms from May to October, but most frequently in spring or fall. The flowers are about 1 inch across, with two larger showy blue petals and one much smaller white petal.  Lasting only a day, several of these ephemeral blooms occur on one plant, generally one at a time, each opening 3 to 4 days apart.  Often found growing in dry scrub and partly shaded woods, its other common names include Widow’s Tears and White-mouth Dayflower.

Blue Curls, also known as Caterpillars, Fiddleneck, or Spike Phacelia, is a leafy annual or biennial that grows 1 to 3 feet tall in sandy or rocky soil.  Its periwinkle blue, bell-shaped flowers are ¼ inch long and occur in numerous slender, coiled clusters that uncurl as the buds develop, resembling the suckered underside of an octopus tentacle.  Its leaves are soft and deeply cut, often appearing ragged, borne on a brittle stem.  Blooming from March to May, Blue Curls is often found in large colonies in meadows and woodland edges.

Texas Bluestar, Amsonia ciliata
Growing up to 2 feet tall, Texas Bluestar blooms from March to June in dry open woods and on chalky hills.  Its narrow almost needle-like leaves occur singly but close together all long the stem up to the flower cluster.  Every cluster is made up of few to numerous pale blue flowers, each ½ inch long and wide, with a narrow tube opening into 5 petal-like lobes shaped like a star, with a ring of white at the center.  It is also known as Fringed Bluestar, referring to the fringe of small hairs found on the new leaves and plant stems. 

Less than 10 percent of the more than 280,000 species of flowering plants on Earth produce blue flowers.  Interestingly, while blue did not develop as a common color during the process of natural selection, plants that have blue blooms don’t seem to deter beneficial pollinators.  Both birds and insects can widely detect blue wavelengths, and blue flowers are just as capable of producing food as flowers of other colors. 

Friday, March 20, 2020

Risky Lilies

Death Camas amid the grasses
Primarily due to their inability to move around to escape danger, plants have developed an array of weapons to defend themselves against predators.  Some defenses are physical, such as thorns or stinging hairs, and others are chemical, mostly in the form of poisons or toxins.  After these harmful chemicals are produced by the plants, they are locked away in parts of the its cells called vacuoles, spaces within the cell that are enclosed by a membrane, protecting the plant from contamination.

The most common way that people or animals come in contact with poisonous plants is to accidentally eat them.  While we don’t normally eat the plants in our landscapes, widely planted ornamentals that are non-native and toxic include oleander, daffodil, elephant ear, iris, wisteria, and azalea.  Native plants can be toxic too, and there are two species in the Lily Family blooming this time of year that are fairly common but known to be toxic. They are Death Camas (Zigadenus nuttallii) and Crow Poison (Nothoscordum bivalve), and just their common names give them away!

The clustered flower head of Death Camas
Death Camas, also known as Nuttall’s Death Camas, Poison Camas, Poison-onion, and Poison Sego, is a perennial flower growing 1 to 2 feet tall, with narrow basal leaves up to 15 inches long.  A stout stem arises from a large, black-coated bulb, with a round-topped cluster of up to 60 cream-colored, 0.5 inch blooms growing around the top.  It blooms from February to April and is found in open prairies, woodland edges, and rocky hillsides in central and northeast Texas.  

Death Camas is a good early nectar source for butterflies
All parts of this plant are poisonous, even when dry.  While unpalatable, livestock has been known to eat it, but typically only in early spring when not much else is available.  While not in the same genus as edible Camas (Camassia sp.), humans have been poisoned, mistaking the bulbs for wild onion. 

Crow Poison is often mistaken for wild onion

Crow Poison, also known as Crowpoison and False Garlic, is one of the first flowers to appear in early spring throughout most of Texas.  Looking much like wild onion, it grows from a bulb but has fewer, larger white flowers about 0.5 inch across in loose clusters atop 8 to 16 inch stalks, and lacks the characteristic onion odor when crushed. Its basal leaves are narrow and 4 to 15 inches long, and it is found in lawns, open slopes, prairies, disturbed sites, open woodlands, and roadsides, where it often forms large colonies.  

Crow Poison blooms in loose clusters
When dug up, it will have a cluster of attached bulbs underground.  While this plant is minimally toxic to humans, it gets its common name from grain farmers’ past practice of crushing its bulbs and mixing them with a handful of grain to be left out for crows to eat.  In turn, the crows would get sick, with some dying, signaling the surviving crows to move on to other sources of grain. 

Now those are some pretty risky lilies!

Monday, March 2, 2020

Tree Serpents

Rough Greensnakes are excellent climbers.
One of the most beautiful and harmless snakes in Texas is the aptly named Rough Greensnake (Opheodrys aestivus).  Its genus is derived from the Greek ophios meaning ‘serpent’, and drys meaning ‘tree.’  It has a 22 to 32 inch long and slender bright green body, which fades to yellow or yellow-green on the sides near its abdomen.  Common to the eastern two-thirds of Texas, this snake is also colloquially called grass snake, green tree snake, and vine snake, but it gets its most recognized common name from its dorsal or topside scales, which are rough or ‘keeled’, having a ridge down the center rather than being smooth.

Primarily arboreal, the Rough Greensnake is found in open deciduous forest, pastures, and suburban gardens, most frequently those adjoining a watercourse such as a creek, stream, lake, river, or upland ravine.  It climbs into bushes, shrubs, and trees, favoring those with horizontal rather than vertical growth, both for protection and to forage for food.   It hunts crickets, grasshoppers, and spiders, as well as caterpillars of butterflies and moths.  Rough Greensnakes are diurnal, and they sleep at night coiled up on branches of vegetation.  Active most months of the year except for December through February, they take refuge in the cooler months hiding under rocks, logs, or debris.

Rough Greensnakes are also called 'grass snakes', due to their
bright green bodies that fade to yellow on their sides and abdomen.
One of the most curious facts about this snake, and others in this genus, is that they turn blue shortly after death.  Yellow pigment combines with blue pigment to give the snake its vibrant green color during life, but when it dies, the yellow pigment breaks down quickly and only the blue pigment remains.  Rough Greensnakes may be confused with Smooth Greensnakes (O. vernalis), but the latter, while similar in color, is shorter in length, has smooth dorsal scales, and occurs only as a relict population along the Gulf Coast of Texas.

While Rough Greensnakes become active as early as March, they mate in June and July, with females laying clutches of eggs in the second half of summer, typically in a depression under a flat rock.  Incubation is short – only 4 to 24 days – since embryonic development begins while the eggs are still in the female’s body.  These snakes can be most active in August or September, when the young emerge and are foraging for food, often in grassy lawns.  Be alert for these snakes when mowing grass at this time of year, as they are beautiful, harmless, and beneficial creatures!