Pollen Positives

 

Giant Ragweed, the bane of many fall allergy sufferers.

While fall is welcomed for the relief it gives from the long, hot summer, it is also a season when allergies run rampant.  These allergies are caused by various pollens, and those who suffer might wonder if there are any positives to pollen at all.  The answer is yes!

The definition of pollen is a fine, powdery substance consisting of microscopic grains discharged from the male part of a plant.  It is necessary for reproduction, and is transported by the wind, insects, or other animals. The grains from each species have a distinct symmetrical shape, surface pattern, and overall structure, and are easily recognizable under a microscope.  Due to their high resistance to decay, pollens have been commonly found in both recent and ancient geologic sediments.  In fact, the study of plant pollen in both living and fossil form is known as palynology. Since pollen is produced in large quantities at certain times of the year, it is often a significant component of the Earth’s atmosphere.

Scanning Electron Microscope (SEM) image of pollen grains, showing their unique shapes. (Credit: Dartmouth College, Electron Microscope Facility)

Many flowering plants produce all-important nectar, but it is pollen that is the most highly nutritious offering, consumed by virtually all bees, as well as beetles, flies, butterflies, birds, and mammals. Most plants produce pollen in excess, to ensure that at least some of it is used for pollination.  Pollination occurs when pollen is transferred from the male anther (fertilizing organ) of a flower to the female stigma (receptive tip of the pistil) of the same flower or one nearby.  This is often accomplished with the help of the animal pollinators listed above. This time of year, the plants that produce the most pollen are Giant Ragweed (Ambrosia trifida) and Cedar Elm (Ulmus crassifolia).

Like all ragweed species, Giant Ragweed is in the genus Ambrosia, because it was long ago believed that it would grant immortality or eternal youth to those who consumed it. Giant Ragweed can grow from 6 to 20 feet tall, especially in roadsides and disturbed areas. Flowering occurs from June to October, with inflorescences forming a spike or spikes made up of many tiny flowers at the top of the plant. These flowers are wind-pollinated, releasing copious amounts of pollen in the fall, eventually developing into small burs tipped with several miniscule spines. 

Giant Ragweed flowers.

Giant Ragweed seeds (burs).

Unlike many other tree species, Cedar Elms flower from late summer to early fall, usually July through September. Their flowers are tiny, pale reddish-purple, lacking petals, and they appear in clusters at the leaf axils. They are wind-pollinated, and after pollination they develop into flat, oval, winged seeds called samaras, which are an important food source for deer, squirrels, and birds. This fall flowering and fruiting is a distinctive feature of Cedar Elms and helps to distinguish them from other native elm species.  They are called ‘cedar’ elms for their propensity to grow in the same habitat as Ashe Junipers, which are colloquially (but incorrectly) called ‘cedars.’

Cedar Elm flowers.

Cedar Elm seeds (samaras).

Pollen plays a critical role in plant reproduction, and is a nutrient-dense resource for bees and other animals.  For humans, a vast number of crops depend on pollination for their existence, including one-third of the world’s food crops such as almonds, chocolate, and coffee.  Due to their regular reproduction cycles requiring pollen, plants sustain ecosystem services such as moderating temperature by providing shade and releasing moisture into the air, producing oxygen, stabilizing soil, and creating wildlife habitat.  That’s how pollen is positive for us and for the environment!

Charismatic Clematis

 

Scarlet Clematis is endemic to the southeastern Edwards Plateau.

Blooming vines are always a welcome addition to our Hill Country landscapes, offering continuous interest through vibrant colors and varied bloom times. Some of the most popular vines are in the genus Clematis in the Buttercup Family.  While many cultivars and hybrids exist, there are nine native species in Texas, the most prominent being Scarlet Clematis (Clematis texensis), Purple Leatherflower (Clematis pitcheri), and Old Man’s Beard (Clematis drummondii).

Otherwise referred to as Scarlet Leatherflower and Texas Clematis, Scarlet Clematis is a herbaceous to slightly woody vine, with compound leaves of four to five pairs of rounded leaflets, and grasping tendrils which allow the plant to climb to about 10 feet.  It has bell-shaped flowers, held in axillary clusters of one to seven, blooming only on new growth.  The four red to scarlet-colored ‘petals’ are actually thick, leather-like sepals slightly recurved at the tips, occurring from March to August.  A ball of feathery plumed seeds follows the floral display.  Scarlet Clematis is uncommon, found along streams and on limestone cliffs and rocky slopes and is endemic to only a few counties in the southeastern portion of the Edwards Plateau.

Scarlet Clematis Bloom

Feathery Plumed Scarlet Clematis Seedhead

Purple Leatherflower, also called Purple Clematis, Bellflower Clematis, and Pitcher’s Clematis, is a 10 foot or longer vine that climbs via twining petioles. Its compound leaves are also comprised of three to five pairs of pointed leaflets, each having a raised network of veins on the underside. From May to September, flowers appear on long, nodding stems arising from the leaf axils, and are dull purple on the outside and dark purple on the inside. The four petal-like sepals are thick and united at the base, but are recurved at the tips.  While they also turn into a ball of plumed seeds following flowering, they are the least pubescent of the native species.  Purple Leatherflower can be found in woodland edges and thickets in the central, south, and western parts of the state.

Purple Leatherflower

Purple Leatherflower Bloom

Plumed Purple Leatherflower Seedhead

Known as Texas Virgin’s Bower and Drummond’s Clematis, Old Man’s Beard is a climbing vine to 30 feet, coiling its petioles along fences and other structures and shrubs.  The compound leaves are composed of five to seven coarsely cut leaflets. From April to September, star-shaped blooms of four light greenish-yellow, almost white, narrow and thin sepals with slightly crinkled margins surround conspicuously long stamens. Old Man’s Beard can be found along roadsides and in rocky canyons in the central, south, and western parts of the state. One of its common names comes from the 2 to 4 inch long, silky hairs on the seed cluster, giving the plant a bearded appearance which often lingers into winter. Another comes from the abundant cascade of white flowers, believed to symbolize purity and innocence.

Old Man's Beard

Old Man's Beard Bloom

Beard-like Old Man's Bloom Seedheads

Flowering Clematis vines have been known to symbolize ingenuity, cleverness, and travel, due to their climbing, rambling nature.  In traditional Chinese symbolism they represent wisdom and foresight, and in Japanese Hanakotoba or the language of flowers, they represent moral beauty and the joy of travelers. The intricacies of their showy flowers and long blooming season make Clematis some of our most charismatic vines!   

Aerial Assassins

Robber Flies are also called Assassin Flies, and for good reason!

What is that powerfully built, fly-like creature that waits in ambush to catch their prey in flight? It’s a robber fly, otherwise known as an assassin fly, which feeds almost exclusively on other insects, including other flies, beetles, butterflies, moths, bees, ants, dragonflies, damselflies, wasps, grasshoppers, and even some spiders.

Robber flies have stout, spiny legs, short antennae, three simple eyes on the top of their head between two large compound eyes, bristly bodies, and a short, stout proboscis that encloses a sharp, sucking mouthpart called a hypopharynx. They also have a dense moustache of bristles on the face called the mystax, which appears to offer some protection from their struggling prey. These flies attack their prey by stabbing it with the proboscis and injecting it with a saliva that contains both a neurotoxin and proteolytic enzymes.  This paralyzes the prey and liquifies the insides, allowing the robber fly to suck the material up through their proboscis.

In spring and summer in our area, some of the more common robber flies include the Bee-like Robber Fly (Laphria macquarti), Prairie Robber Fly (Diogmites angustipennis), and the Maroon-legged Robber Fly (Promachus hinei). 

The Bee-like Robber Fly is large (up to 1.25” long), hairy, mostly black with a yellow thorax, basal abdominal segments, and some yellow on the legs.  It mimics the American Bumblebee, and while it prefers to feed on small beetles, it will take a wide range of prey, often perching on tree stumps in the open.

Bee-like Robber Fly

The Prairie Robber Fly, also called the Slender-winged Hanging Thief, is about 1” long, with greenish-red eyes, tan to reddish-brown body, thorax with darker brown longitudinal stripes, and abdomen with darker lateral stripes.  It is common in both woodland and meadows, hunting bees and other insects, and typically hangs from vegetation by its forelegs while it consumes its prey.

Prairie Robber Fly

Another large robber fly is the Maroon-legged Robber Fly, up to 1.5” in length.  It has dark eyes, light-colored bristles around the face, a brown thorax, a cream-colored abdomen with thick black bands and a black tip, and hairy reddish-brown legs. It prefers hunting bees and wasps, and can be found flying around a variety of habitats, perching on the ground or in vegetation.

Mating Maroon-legged Robber Flies

Female robber flies deposit tiny, whitish eggs on low-lying plants and grasses, or in cervices in wood or bark, or in soil. After hatching, the larvae live in this detritus, feeding on other soft-bodied insects. Robber flies overwinter as larvae, pupate in the soil, and eventually emerge as adults.  This developmental cycle can take one to three years, depending on the species and environmental conditions. Robber flies generally occur in relatively open habitats with scattered vegetation, or in forested margins and woodland edges.  

Robber flies are generally considered beneficial insects due to their predatory nature, as they primarily feed on other insects, many of which are considered pests. These aerial assassins help to naturally regulate insect populations thereby contributing to a more balanced ecosystem!

Masterful Mallow

 

Turk's Cap is a wonderful native plant for a summer garden.

In the heat of a central Texas summer, few plants are as versatile as Drummond’s Turk’s Cap (Malvaviscus arboreus var. drummondii).  Also known simply as Turk’s Cap, Texas Mallow, Sleeping Hibiscus, or Manzanilla, this hardy native plant provides color, shade, and food for a variety of species.

For humans, Turk’s Cap is a gardener’s delight.  It thrives in woodland edges and limestone slopes in partially shaded sites, and does especially well under oaks or junipers.  It is drought-hardy, requiring little water once established, and blooms profusely from May to November.  It is a deciduous shrub, to 4 feet, spreading via roots but easily controlled.  Its leaves are alternate, simple, and roughly heart-shaped, with 3 to 5 shallow lobes.

A top down view of the five whorled petals of a Turk's Cap flower.

Turk's Cap produces small, edible, apple-like fruits.

The most common name of Turk’s Cap comes from its bright red flowers, comprised of 5 overlapping whorled petals, up to 2 inches long including the protruding stamen, and resembling a Turkish turban. They also look like small, closed versions of a hibiscus flower, hence the name Sleeping Hibiscus. These flowers develop into red, 1 inch wide, 5-lobed, apple-like fruits, giving the plant yet another common name of Manzanilla, meaning “little apple.” These fruits are edible for humans and wildlife and taste like watermelon.

An adult Turk's-cap White-Skipper butterfly.

Turk’s Cap is a host plant for several butterflies and moths, meaning the females lay their eggs on this species so their caterpillars can feed on it. Turk’s-cap White-Skipper (more common in south Texas), Io Moth, Yellow Scallop Moth, Straight-lined Mallow Moth, Cotton Tipworm Moth, and Window-winged Moth. Caterpillars eat different parts of the plant, from the tender young leaves to the flowers and fruits.  Young caterpillars hide in crevices on the host plant, while older ones live in shelters made of leaves. 

An Orange-barred Sulphur inserts its long proboscis into the flower.

Hummingbird beaks are the perfect shape to reach the
flower's nectar.

Turk’s Cap also does double duty as a nectar plant, for those animals that can find a way to access its sweet nectar.  Larger butterflies such as the Orange-barred Sulphur can reach into the flower with a long tongue or proboscis, hummingbirds such as the Black-chinned Hummingbird can uses its long and slender, straw-like beak, and some bumblebees and carpenter bees have strong mouthparts that can chew a hole or slit at the base of the flower where the nectar resides.

Bumblebees can access the nectar by cutting through the flower's base.

And some bumblebees just dive in head first!

The leaves of Turk’s Cap have been used in the past as an emollient to treat inflammation, aid digestion, soften skin, and soothe itching. The flowers can be used to make a hibiscus tea, and the fruits can be made into a delightful syrup or jelly. Now that you know all about the wonderful aspects of this masterful mallow, consider planting it in your garden this coming fall!

Roving Ringtails

Raccoon or Ringtail?

The common but elusive Ringtail or Ringtail Cat (Bassariscus astutus) is not a cat at all, but a member of the Procyonidae Family and a close relative of the Northern Raccoon.  The origins of its scientific name comes from bassar or ‘fox’, isc or ‘little’, and astute or ‘cunning’. In Texas, it is found mostly in the Trans-Pecos, the Edwards Plateau, and the Cross Timbers regions.   

An adult Ringtail on our back porch railing.

While ringtails are cat-sized mammals, their face is fox-like with a pointed snout, their body is elongated, and their tail resembles a raccoon.  The ears are large, and their big, dark eyes are each surrounded by a patch of light-colored fur.  The fur on their body is buff to brown-colored above and whitish below, with a spectacularly bushy, ringed tail.  This tail is often longer than their body, and is marked by a series of 14 to 16 alternating black and white rings (black rings incomplete on the underside) with a black tip.  

Close-up of the face of a Ringtail.

Mainly nocturnal but sometimes seen at dawn and dusk (crepuscular), ringtails are roving, solitary mammals that come together only to mate.  Their breeding season starts in late February and continues to mid-April, and females are in heat for only one 24-hour period during this time.  In early May to mid-June 2 to 4 cubs are born fuzzy, white-haired, and with a tail that is not yet colored with the distinctive black and white bands.  The cubs open their eyes at one month, and at four months begin hunting for rodents, insects, lizards, birds, and berries.  Ringtails are quite vocal, especially the young, and will make a variety of sounds including squeaks, chatters, grunts, growls, and hisses, with the typical call being a loud, plaintive bark.  In the wild, ringtails live an average of seven years. 

This Ringtail is eating sunflower seed that has fallen out of our bird feeders.

Ringtails can be found in our oak-juniper woodlands that have rocky areas associated with water, including riparian canyons and caves, limestone cliffs, and sometimes in man-made structures like mine shafts.  They can den in tree hollows, rock crevices, other animals’ abandoned burrows, and even seldom-used spaces in buildings.  They roam frequently, rarely spending more than three straight nights in one den.  Interestingly, the ankle joint of the Ringtail is very flexible and is able to rotate over 180 degrees, which makes them very agile climbers.  By pressing their feet against one wall and their back against the opposite wall, or by pressing both right feet against one wall and both left feet against the opposite wall, they are able to ‘stem’ or ascend/descend narrow passageways and wide cracks in the rock.  Their strong tail can provide balance for negotiating narrow ledges and limbs, and even allows them to reverse direction by performing a cartwheel!       

Getting access to our bird bath is an easy feat for the agile Ringtail!

Ringtails have many other common names, including Miner’s Cat, as they were often kept by miners and settlers as pets, to keep their cabin free of mice.  A hole was cut in a small box that was placed near a stove or fireplace, which acted as a dark, warm place for them to sleep during the day, and they returned the favor at night, hunting mice and keeping them and other rodents at bay.  In the native language of the Nahuatl Indians of Mexico, ringtails were called cacomistle, which is derived from the word tlahcomiztli meaning ‘half mountain lion.’  Whatever you call them, consider yourself lucky should you spot one of these beautiful, timid, and rarely seen nocturnal mammals!  

Neither Hummingbird nor Bumblebee

 

Hummingbird or bumblebee?  Neither!

Take a closer look when you see what you think is a small hummingbird hovering about and nectaring on the tubular flowers in your garden.  It just might be a Snowberry Clearwing (Hemaris diffinis), one of our more common hummingbird moths.  

Moths in the genus Hemaris are often generically called hummingbird moths, due to their ability to fly and move just like hummingbirds. They are rather plump moths, and the tip of their abdomen opens a bit like a fan. Many are brown or black with some yellow, so they are also good bumblebee mimics. Several species have clear wings, as they lack as many wing scales as other lepidopterans, and they actually lose the ones they do have shortly after they emerge due to their highly active flight tendencies.  

This adult Snowberry Clearwing just emerged from a winter spent in leaf litter,
still with all the scales on its wings.

The Snowberry Clearwing is about 1.25 to 2 inches in length, with a yellowish thorax above, a black abdomen with a yellowish band near the tip often split in two, and the namesake clear wings. Like other hummingbird moths, they generally fly during the day, but may continue into the evening if they have found a particularly good nectar source. Their proboscis or sucking mouthpart is quite long, so they prefer to sip from tube-shaped flowers. 

An adult Snowberry Clearwing showing its yellow thorax, black abdomen with a
yellow stripe, and signature clear wings.

The adults start flying in March after emerging from the leaf litter beneath their host plant where they spend the winter as a pupa protected by loose silken cocoon.  Females attract males by broadcasting a pheromone from the glands at the tip of the abdomen, and after mating, they lay individual, tiny, round green eggs on the underside of the leaves of the host plant.  In the south, they typically produce more than one generation each summer, flying well into November.

The common name for the Snowberry Clearwing comes from the fact that it was first described in 1836 in the northeast, where it uses Common Snowberry (Symphoricarpos albus) as a host plant, a native plant in the Honeysuckle family that grows in the northern half of North America. In the southern US, the preferred native host plant for this moth is Coral Honeysuckle (Lonicera sempervirens), which can be purchased at most native plant nurseries.  It is a high-climbing, twining vine to 20 feet long, with smooth, paired semi-evergreen leaves and clusters of red, tubular flowers.  In the wild, they also use our native White Bush Honeysuckle (L. albiflora), which is more shrub-like with twining branches that have smooth, paired deciduous leaves and clusters of creamy white tubular flowers.

Coral Honeysuckle

White Bush Honeysuckle

The larva or caterpillars of the Snowberry Clearwing are commonly called hornworms, due to the horn-like projection on their posterior end.  They are up to 2 inches long, blue-green above and yellow-green along the sides, with black spots and a black horn.  Uncommonly, they can also take a brown form with the same black spots and horn.  They match the foliage of their host plants so well that they are often very difficult to find. 

Snowberry Clearwing larva, green form.

Snowberry Clearing larva, brown form.

Why Insects Matter

 

Insects are terrific pollinators!

As the growing human population transforms our planet, the global insect population is declining at an unprecedented rate of 2% a year. The world has lost 5% to 10% of all insect species just in the last 150 years, so in 40 more years we could lose one third of all insect species. In a study just published in the journal Science, a working group called the ‘Status of Butterflies in the U.S.’ found that the total abundance of butterflies in the U.S. declined by 22% from 2000 to 2020.  Said another way, one in five butterflies have vanished.

Many butterfly species, including the Monarch, are declining in abundance.

What is driving this precipitous drop in insect populations and why does it matter? Insect populations are struggling due to several factors, including deforestation/habitat loss (due to development), non-native invasive species, pesticide use, artificial light pollution, and climate change.  As a result, the populations of other animals, crops, and flowers that rely on insects to survive also struggle.

Non-native, invasive plants, like Ligustrum species, often overtake native habitats.

Scientists say that it is impossible to have an insect-free life on this planet. They perform many essential services that are vital for humans’ quality of life. Pollinators such as bees, butterflies, moths, and many other types of insects are necessary to produce diversity and abundance in our food supply, including crops such as coffee, chocolate, blueberries, apples, almonds, avocados, and pumpkins, just to name a few. In fact, pollinators help ensure that about 75% of the world’s flowering plants and 35% of the world’s food crops are produced.  Other scientists estimate that one out of every three bites of human food are directly related to the work of pollinators such as bees, butterflies, moths, beetles, and other insects.

Moths and beetles are pollinators, too!

Plant and animal waste would pile up if it weren’t for the services of dung beetles and other insect recyclers. Insects like dragonflies, ladybugs, green lacewings, ground beetles, and parasitic wasps keep what we call the ‘pest’ species at bay – the mosquitos, ticks, fleas, lice, and flies that can carry disease as well as crop pests such as armyworms, cutworms, and wireworms.  

Dung Beetles hard at work.

Roseate Skimmer dragonfly eating a mosquito.

Most humans like birds, but most are also unaware of the fact that 96% of birds would not be here without insects. It takes 6,000 to 9,000 caterpillars and other insects to feed a clutch of four to six Carolina Chickadee offspring. Multiply that by the fact that most all avian nestlings and fledglings eat some form of insects, and you very quickly realize how important they are to the food web. Insects are also the main food for all of the fish, so they are the glue that binds together every terrestrial and freshwater ecosystem on the planet.

Many bird species, like the endangered Golden-cheeked Warbler,
feed insects to their young.

What can be done to reduce this downward trend?  The good news is that the things we do in our own backyards can actually make a difference when it comes to insect conservation. First and foremost, reduce or (better yet) replace your non-native lawn with native plants.  Lawns make up about 50% of Austin’s green space, so turning them back into native plantings would provide significant benefit to insects. 

Replace your lawn with native plants -
extra bonus for providing water!

Eliminate all pesticide use, including mosquito spraying. The spray contains pyrethroids which are advertised as “safe as chrysanthemum flowers”, but they are a much stronger synthetic version that is chemically designed to be more toxic with longer breakdown times.  This increased potency compromises the human body’s ability to detoxify the pesticide in addition to killing all insects, not just mosquitos.

Mosquito spraying kills all insects,
not just mosquitos.

Light pollution contributes to insect decline.

And last, but not least, turn your exterior lights off at night so as not to affect the behavior of night-flying insects (this also benefits birds during spring and fall migration). Artificial lighting can disorient moths and confuse their sense of direction, causing one third of those that swirl around a light at night to die from exhaustion or predation. Excess light also disrupts the mating flashes of fireflies and confuses insects like mayflies by bouncing light off of asphalt and causing them to lay their eggs in the street instead of in a lake or stream.