Monday, June 4, 2018

Whiptails & Racerunners

Common Spotted Whiptail
Small to medium-sized slender lizards, whiptails and racerunners can be distinguished from other lizard species by their generally granular dorsal (topside) scales, larger rectangular ventral (underside) scales arranged in transverse rows, long tails, and forked, snake-like tongues. Additionally, these species belong to the genus Aspidoscelis, from the Greek aspido or ‘shield’ and skelos or ‘leg’, relating to their well-developed limbs that enable them to sprint at rapid speeds. Terrestrial and diurnal, these lizards are primarily carnivorous or insectivorous, actively foraging for food while temperatures are warm, and quickly skirting between objects for cover.  Of the 22 species occurring in the southwest, Central Texas is home to the Common Spotted Whiptail (Aspidoscelis gularis) and Six-lined Racerunner (Aspidoscelis sexlineata).  

Common Spotted Whiptail

The Common Spotted Whiptail has a brownish-green body with 7 to 8 longitudinal yellowish-white stripes and similarly colored spots in the margins.  Its tail is up to twice the length of its body, reaching a total length of just about 12 inches.  It is found in prairies, grasslands, rocky hillsides, dense thickets, and canyon bottoms, often near water.  Males are larger than females, having a red, orange, or pinkish throat and sometimes a blue or light blue belly.  Females have a white or cream-colored underside, and lay 1 to 8 eggs in July, typically in a separate chamber of their underground burrow, sometimes as deep as 11 inches.  These lizards scare easily and often retreat in a straight line, but can best be viewed from April through August when their insect prey are most abundant.

Six-lined Racerunner
Just over 10 inches long, the Six-lined Racerunner has seven light dorsal stripes with a greenish wash on the head and upper body that fades to brown posteriorly.  Males may also have a blue throat and belly, and juveniles often have more distinct stripes, lack the green wash, but have a bright blue tail. Females lay clutches of 1 to 6 eggs from May to August.  Associated more with sandy soils, this lizard can occupy a wide variety of habitats, including grasslands, riverbanks, floodplains, and juniper woodlands.  Spiders and grasshoppers are their chief prey, and adults actively forage during the day, but as summer temperatures rise by July, their activity becomes bimodal, peaking in the morning and late afternoon to avoid the hottest parts of the day.

Common Spotted Whiptail growing a new tail
Like many lizards, whiptails and racerunners have developed the ability to allow the tail to break free of the body when grasped by a predator. Called tail autonomy, this process involves wriggling the detached tail to distract the predator while the lizard itself is able to escape. Complex adaptations have evolved to enable the tail to be released along a series of fracture planes, which usually occur through weakened vertebrae, and not between them. Most amazingly, these species also have the ability to regenerate the tail, albeit slowly, so it can be lost again if necessary.

Friday, May 25, 2018

Distinctly Different Milkweeds

Pearl Milkvine
Much ado has been made of the more common and widespread milkweed species, but there are a handful of milkweed vines that are less common but more distinct, and just as useful as native host plants for Monarchs and related butterflies.

A fairly robust, twining vine 6 to 12 feet long growing in dry, light shade in thickets on rocky hillsides and woodland edges, Pearl Milkvine (Matelea reticulata) is best known for its heart-shaped leaves and flat, greenish-white flowers ½ to ¾ of an inch across with pearly, iridescent centers.   Also called Green Milkweed Vine, Net Vine Milkvine, and Netted Milkvine, its curious flowers have tiny white veins forming an intricate pattern on the surface of the petals, adding to their unusual look. In fact, ‘reticulata’ refers to this pattern, which mans ‘resembling a net or network’.  It blooms from April to July, especially in full sun, giving way to fairly large, interesting prickly follicles filled with seeds attached to silky threads.  This native species is a host plant to Monarch butterflies.

Plateau Milkvine

Both the Pearl Milkvine and Plateau Milkvine have prickly seed follicles
Often mistaken for Pearl Milkvine is Plateau Milkvine (Matelea edwardensis), endemic only to the Edwards Plateau of Central Texas.  This uncommon vine shares the same twining habit of Pearl Milkvine, but its leaves, while similar, generally have a somewhat wavy edge, and its flowers are bell-shaped instead of flat.  Additionally, its greenish-white flowers do not have a pearl center, and its petals are not solely reticulate-patterned, having parallel veins in their lower halves and centers, and reticulate or networked veins only on the edges or margins.  Blooming in April and May, this species can be found on gravelly soils in open woodlands, often climbing on other plants, and it is a native host plant for Queen butterflies.

Pearl Milkvine Flowers
Plateau Milkvine Flowers
Purple Milkvine
Usually found in the chalky soils of pastures and open ground, Purple Milkvine (Matelea biflora) has low-growing stems that radiate along the ground from a woody rootstock, and along with its opposite, triangular leaves, are covered with long, spreading hairs.  From March to June, pairs of star-shaped, five-petaled, dark purple-brown flowers rise from the base of the leaves, which gives this plant its other common name of Star Milkvine.  While its trailing stems can grow up to 2 feet long, it inhabits grassy areas and as such is often hidden and overlooked, except by Queen and Soldier butterflies who use it as their native host plant.

Named for a small town in Chihuahua, Mexico, Talayote (Cynanchum racemosum) or Milkweed Vine is a climber that grows to 15 to 20 feet in full sun to part shade, and is a native host plant for both Queen and Soldier butterflies.  Talayote produces clusters of small cream and green flowers that are held above and among the heart-shaped leaves, blooming in the hotter months from summer into fall, and attracting a host of other small but beneficial pollinators.  Growing only in Central, South, and West Texas in the United States, this vine produces plump, smooth follicles 3 inches long, filled with silk-topped seeds, often remaining on the vine well into winter. 

Take the time to seek out and appreciate these lesser known members of the Milkweed family, as they are beautifully and distinctly different!

Tuesday, May 1, 2018

A Horse of a Different Color

Horsetail or Scouring Rush

Few plant species that grow naturally today have been around for over 100 million years, but one of the best known are plants in the genus Equisetum, which is the only living genus of the entire family of Equisetopsida, most commonly known as horsetails.  They are recognized as close relatives of ferns, typically growing in wetter areas with whorls of needle-like branches radiating at regular intervals from each single vertical stem.

The common name of horsetail is used for the entire group of plants, since the branched species resemble a horse’s tail.  In fact, the genus Equisetum comes from the Latin equus or ‘horse’ and seta or ‘bristle.’  Another common name is scouring rush, referring to the upright rush-like appearance of the plants, and the fact that the longitudinal ridges of the stems are coated with abrasive silicates, making them useful for scouring or cleaning metal items.  It is still used today as a traditional polishing material in Japan.

The primary species of horsetail that occurs natively in wet or moist areas of Texas, most commonly on the Edwards Plateau and in Blackland Prairie, as well as most of the non-tropical northern hemisphere, is Equisetum hyemale.  A spreading, reed-like perennial growing to 3 feet tall, each stem is evergreen, cylindrical, jointed, hollow, and about 1/4 of an inch in diameter.  In this species, the needle-like branches appear non-existent, but are actually small and fused around the stem at each joint or node, forming a blackish-green band or sheath.  Interestingly, the pattern of spacing of the nodes in these plants, which grow increasingly close together toward the apex, is precisely what inspired Scottish mathematician John Napier to discover logarithms in the late 16th century.

Dragonflies, like this Neon Skimmer, love to perch on the cones of
the horsetail’s upright stems.

Horsetail prefers open or wooded areas along streams, moist flats, and wet ledges. Like ferns and other related species, horsetails reproduce by spores rather than through seed-producing flowers. These spores are borne in cone-like structures at the tips of some stems, and are mostly homosporus, meaning of the same size and type.  The tiny spores have four elaters or structures that alter shape in response to changes in moisture, effectively acting as moisture-sensitive springs that assist spore dispersal through crawling and hopping motions once released from the cone.

Horsetails reproduce by spores borne in the cone-
like structures at the tips of some stems.

The upright, evergreen, segmented foliage of horsetail is an appropriate plant for a rain garden, pond edge, water feature, or area with moist soil, and is an excellent perching plant for dragonflies. While it can spread quickly by underground or underwater runners, it is easily kept in check by periodic pulling or by planting it in a container.  Few plants add as much interest or vertical structure to a wildscape as this living fossil, which is clearly a  ‘horse of a different color’!

Friday, April 6, 2018

Blazing Beetles

Big Sand Tiger Beetle, Cicindela formosa
Over 2500 species and subspecies of tiger beetles are currently described worldwide, with more than 45 species occurring in Texas.  Tiger beetles get their name from their cat-like predatory behavior, performing an unusual form of pursuit where they alternatively sprint quickly toward their prey then stop and visually reorient, eventually running down their target.  In fact, some tiger beetles can run at a blazing speed of 5 mph, and are considered one of the fastest running land animals for their size!

Tiger beetles are believed to be closely related to ground beetles, but they differ in terms of their proportions.  Tiger beetles are about one inch long on average, with a head wider than its thorax, which is located between the head and the abdomen.  They also have large bulging eyes, long spindly legs, and oversized sickle-shaped mandibles to grab prey and devour it on the spot.  Tiger beetles are important predators in the insect world, feeding on a wide variety of ants, beetles, grasshopper nymphs, flies, and spiders.  They are most often found in sandy areas, stream edges, clay banks, and woodland paths.  Many are active in the daytime, and the colors and patterns on their oblong elytra (or wing covers) are often iridescent and striking. 

Festive Tiger Beetle, Cicindela scuterllaris
Some of the more common tiger beetles in our area include members of the Cicindela genus, which comes from the Latin and means ‘glowworm’, referring to the fact that most of these species have metallic, flashy elytra.  In Eastern and Central Texas, the Big Sand Tiger Beetle (Cicindela formosa) and Festive Tiger Beetle (Cicindela scutellaris) prefer the dry sandy areas of post oak woodlands.  The Big Sand Tiger Beetle has luminous reddish-purple elytra with irregular white marks around the edges and the Festive Tiger Beetle’s elytra are iridescent reddish-bronze to purple to blue-green or blue-black with reduced or absent spotting.  Both species can be sighted late spring into fall.

Ocellated Tiger Beetle,Cicindela ocellata 
Abundant along water edges, the Ocellated Tiger Beetle (Cicindela ocellata) is most active in the summer, and can be identified by its bronze elytra speckled with 8 cream-colored spots (4 on each elytra).  Ocellated means having one or more ocelli, or eye-like markings. The Six-spotted Tiger Beetle (Cicindela sexguttata) is the probably the most commonly observed species on dirt paths in grassy areas seldom far from woods, and has brilliant green elytra with typically six tiny white spots on the lower half (3 on each elytra). 

Six-spotted Tiger Beetle, Cicindela sexguttata
Tiger beetles are also excellent indicators of environmental quality and are often studied as bioindicators.  Many require undisturbed sandy areas and specific microclimates for their burrows. With rapid urbanization and human disturbance of natural areas, these blazing beetles have fewer places to live and survive.  They are very sensitive to changes in the environment, and are among the first species to react to pesticides, misuse of natural habitat, and climate change.

Friday, March 2, 2018

Early Signs of Spring

Great Purple Hairstreak on Elbowbush (Forestiera pubescens), one
of the earliest plants to bloom, often beginning in February.
A blooming Missouri Violet (Viola missouriensis) is a sure sign
that spring has arrived!
Two-Flower Anemone (Anemone edwardsiana) blooms from February
to April, and prefers the tall grassy banks of moist, shaded canyons.
The yellow blooms of Agarita (Mahonia trifoliolata) appear in
February and March, and eventually form edible red
berries relished by humans and wildlife alike.
In late February and early March, one can often hear flocks
of Sandhill Cranes honking overhead as they make
their way north with the warming weather.
A Juniper Hairstreak sips nectar from the blooms of
an Elbowbush, which is also a favorite plant of native bees.
Texas Redbud (Cercis canadensis L. var. texensis) has clusters
of flowers that appear in early spring before the leaves emerge.
One of the earliest butterflies to appear in spring, Henry's Elfin
utilizes the Texas Redbud as one of its host plants.
Nothing heralds the smell of spring like the heady scent of a
blooming Mexican Plum (Prunus mexicana)!  This small tree is a
must for any pollinator garden.
The Falcate Orangetip is a true springtime butterfly, on the wing
as early as March.

Sunday, February 18, 2018

Marvelous Mahonias

Agarita showing its simple trifoliate leaflets.
One of the constant debates in the botany world is whether or not the genus Mahonia should stand alone or be included in the genus Berberis.  This discussion is based on the fact that several species in both genera are able to hybridize, and when viewed as a whole, no consistent separation exists except for simple versus compound leaves.  Taxonomy debate aside, the two most marvelous Mahonias in Texas are the well-known Agarita (Mahonia trifoliata) and the lesser-known Texas Barberry (Mahonia swaseyi).

Agarita with red berries.
Also called Agarito, Algerita, Laredo Mahonia, Laredo Oregon-grape, Trifoliate Barberry, and Texas Wild Currant, Agarita is a 3 to 8 foot evergreen, thicket-forming shrub with gray-green to blue-gray simple leaves composed of 3 leaflets.  Holly-like, each lobe of the leaflets ends in a sharp spine, and the woody stems are bright yellow inside.  Small yellow flowers appear in February and March, followed by red, berry-like fruits from May to July. Agarita grows throughout most of South-Central and West Texas, and prefers hills, rocky slopes, and open woods that have well-drained but rocky, limestone soils.  Songbirds and small mammals will eat the fruits, and use the prickly plant for cover.  In West Texas Agarita is used as a larval host plant for the Chinati Sheepmoth, one of our native wild silk moths.

’Texas Barberry has a more compound leaf structure.
Texas Barberry, also known as Texas Oregon-grape, is a 3 to 5 foot evergreen shrub with 3 inch long compound leaves composed of 2 to 4 leaflet pairs and one terminal leaflet.  The leaflet edges have spiny teeth and prominent veins on their lower surface.  From February to April yellow flowers appear, producing small orange-red fruits in early summer.  In addition to its leaf arrangement, Texas Barberry differs from Agarita in terms of range.  While it occurs in the Edwards Plateau and in one location in the Texas Panhandle, it is endemic to the Hill Country region, where it grows in full sun to light shade on ridges with rocky, limestone soil.  Texas Barberry is also rare and much less common than Agarita, and its foliage turns reddish-purple in the fall.   

While both of these species of plants are often grown for their spiny evergreen foliage and yellow flowers in early spring, their fruits are edible for humans (as well as wildlife) and are rich in vitamin C, and have been used to make jellies, pies, cobblers, and wines.  While edible, the fruits are highly acidic and should not be eaten raw in large quantities.  Additionally, the wood of these species has been used as a light yellow dye for wool.  

Whether you are looking for a barrier plant, wildlife cover, early bloomer, edible fruits, or just something evergreen that requires little care, look no further than our native, marvelous Mahonias

Sunday, January 21, 2018

A Descent of Woodpeckers

Ladder-backed Woodpecker, male
Known for creeping up tree trunks and drilling into wood to nest and find food, woodpeckers are arboreal birds having a vertical posture, rounded wings, a chisel-shaped bill, short legs with strong claws, and stiff tail feathers.  These features enable them to climb, prey on insects, and feed on nuts and fruits.

A woodpecker uses its tail for support as it moves up a tree trunk.  Stiff, pointed tail feathers reinforced with longitudinal ridges also have small barbs that curve inward towards the tree, allowing the bird to use its tail as a brace.  Its feet are ‘zygodactyl’, meaning two toes facing forward and two toes facing backward, which helps support it when clinging to vertical surfaces. While all woodpecker bills are chisel-shaped, differences in curvature are based on the hardness of the species of wood it excavates as well as the hammering force it uses.  Tongues are also specialized in that they are barbed, sticky, and extremely long for the bird’s head, which reduces the amount of excavation required for foraging.

Ladder-backed Woodpecker, female
One of the most common and noticeable species of woodpecker in our area is the Ladder-backed Woodpecker (Picoides scalaris), which has a black and white barred back, spotted sides, and a face marked with black lines.  The males also sport an extensive reddish crown, while the female’s crown is black.  While it can nest in several types of trees, it most often nests in tall cactus in the western part of the state, giving it the old name of ‘cactus woodpecker.’  Ladder-backed woodpeckers feed on beetle larvae from small trees, but will also eat prickly pear cactus fruits (tunas) and forage on the ground for insects.  When gleaning for insects in trees, the larger male probes and pecks on trunks and larger limbs with his stouter bill, while the female more often concentrates on gleaning bark surfaces on higher branches and outer twigs.

Golden-fronted Woodpecker, female
The Golden-fronted Woodpecker (Melanerpes aurifrons) also has a black and white barred back, but a creamy white to pale yellow breast, a golden orange nape, and a small red cap on the male. A bird found west of the Balcones Escarpment, in flight they show white wing patches, a white rump, and a black tail, often calling as the glide from tree to tree.  They feed on insects, nuts (especially pecans), berries, acorns, and a wide variety of other food items, and only sometimes cache food in bark crevices.  

Downy Woodpecker, female
East of the Balcones Escarpment, the Downy Woodpecker (Picoides pubescens) has black upperparts checked with white on the wings, a boldly striped head, and a broad white stripe down the center of its back.  Its straight, chisel-like bill tends to look smaller than other woodpeckers its size, and the males have a small red patch at the back of the head.  In winter, Downy Woodpeckers are often members of mixed species flocks, allowing them to spend less time watching out for predators and better luck finding sources of food.  

The Red-bellied Woodpecker (Merlanerpes carolinus) has a patterned black and white barred back, barred central tail feathers, and a namesake small reddish patch or tinge on the belly that is often hard to spot.  The males have a solid red crown and nape, while the females only have a red nape.  Common in open woodlands, suburban areas, and parks, these woodpeckers are often seen hitching along branches and tree trunks, sometimes wedging large nuts into bark crevices and whacking them into manageable pieces using their pointed beaks.  

All woodpecker species use simple calls and drumming against tree trunks to communicate.  While the drumming is not a sure-fire way to identify a particular species, it can help you locate an individual bird, and maybe even a flock or descent of woodpeckers!