Cedar-apple Rust

Cedar-apple Rust (Gymnosporangium juniper-virginianae), a parasitic fungus on

 Eastern Red Cedar (Juniperus virginiana). This wood gall produces orange, gelatinous horns

that produce spores of the fungus.

Walk by a Eastern Red Cedar (Juniperus virginiana) in the spring and you may see something weird.  Looking like an extraterrestrial invader among the cedar needles you could see gelatinous orange horns protruding from a small wooden ball.  This is one of the life stages of, not an alien, but a fungus, Cedar-apple Rust (Gymnosporangium juniper-virginianae).   

As the name suggests this fungus infects two different plant species to complete its reproductive cycle.  Some parasites, like the Small Pox Virus, infect only one host, humans.  An infected person would be the host for the virus and could pass the Small Pox Virus to other people.  Because it has a simple reproductive cycle and humans were the only host, a worldwide vaccination campaign has made this once deadly viral disease extinct in the wild.  Other parasites have a more complex life cycle.  The malaria parasite, the protozoan Plasmodium sp., requires two alternate hosts, a mosquito and a warm-blooded animal (like us) to go through its reproductive cycle.  Parasites with complex life cycles are harder to combat.  As its name suggests Cedar-apple Rust needs both a cedar tree and an apple tree, so its life cycle is more like that of malaria. 

 

Cedar-apple Rust on Eastern Red Cedar. The orange
horns are producing spores.  Rowan County, NC.

Cedar-apple Rust on Eastern Red Cedar. 
The orange horns have tried up on this gall. Rowan County, NC.

Cedar trees can have a long-term infection by the fungus.  Cedar-apple Rust spores, produced from the fungus infecting an apple tree, lands on the cedar.  A spore germinates and enters the stem of the cedar.  There is produces hormones that cause the stem to expand into a wood ball of tissue called a gall.  In early spring, the galls put forth their orange horns that bear spores and released them into the air.  The galls may produces several rounds of gelatinous horns during the spring, usually after rain.  Sometimes you can find the fungus covering a whole stem of a cedar.  Cedar trees may bear multiple Cedar-apple Rust galls.  We have one in our yard that looks like it is covered with Christmas decorations during the spring Cedar-apple Rust season. 

Cedar-apple Rust infecting Eastern Red Cedar stems. 
This rust has not yet induced the tree to make a gall.  Rowan County, NC.

An Eastern Red Cedar decorated with many spore
producing galls of Cedar-apple Rust.  Rowan County, NC.

Some of these spores produced on the cedar trees are lucky enough to land on the bud of an apple tree (Malus spp.) and infect the young leaves.  The Cedar-apple Rust infection on apple makes yellow lesions on the leaves.  During late spring and early summer, the fungus makes spores on the apple leaves that float through the air and can infect other cedar trees.  The spores made on the apple are different from those made on the cedar.  Cedar-apple Rust makes four different spore types during the course of its life cycle, only two of which made it into this blog.  Of course, the different spore types each have different names.  Mercifully, I will spare you these spore names. 

Cedar-apple Rust lesions on the upper surface of
an apple tree (Malus spp.) leaf Mecklenburg County, NC.

Cedar-apple Rust lesions on the lower surface of
an apple leaf.  Mecklenburg County, NC. 

Cedar-apple Rust infections can reduce fruit yield in apple orchards.  Apple growers try to remove cedar trees from near their orchards but it is nearly impossible to take out all the cedars trees in an area.  Most growers spray fungicides on their trees to control Cedar-apple Rust and other fungal diseases.   

We are now in the dog days of summer.  The apple phase of  Cedar-apple Rust is releasing spores. The cedar phase of the fungus is keeping a low profile. The galls on cedar phase will produce their strange orange horns again next spring.  Cedar-apple Rust, with its complex life cycle and bizarre spore bearing structures, is strangely beautiful.   This beauty is appreciated more by naturalists than by the apple growers who struggle to raise their crops in the presence of this fungus. 

Bridges and Swallows

Cliff Swallows (Petrochelidon pyrrhonota)
building nests under a highway bridge.  Davie County, NC.

Bridges can be engineering marvels and architectural masterpieces.  Think Tower Bridge, Pont Neuf, Golden Gate Bridge and Brooklyn Bridge.  But even humble bridges can host treasures.  On a highway bridge over a small river near our home there is a nesting colony of Cliff Swallows.  Over 100 of these fast-flying aerialists are raising the next generation under this bridge.  Like bridges, the nests of Cliff Swallows are architectural wonders.

Video of Cliff Swallows collecting mud

to use in nest building.  Davie County, NC.

                        

Completed Cliff Swallow nest.  Davie County, NC. 

Cliff Swallows (Petrochelidon pyrrhonota) are small birds that are white below, with an iridescent blue back, an orange rump, reddish-brown face and a blue cap.  Just above the beak, in the center of their foreheads, they have an off-white spot, rather like the headlight of a motorcycle.  Cliff Swallows make their living by catching insects on the wing, giving their chattering call all the while.  They are neotropical migrants, returning each spring from their winter in South America.  Unlike most small birds that migrate at night, swallows migrate during the daytime and feed en route.   

 

Cliff Swallow engaged in nest building. This adult bird shows the spot
on its forehead  Davie County, NC.

 Cliff Swallows making nests.  Davie County, NC.

Originally, Cliff Swallows nested  (of course) on cliffs and were infrequent summer residents in the Southeastern United States.  But human structures, particularly bridges, have allowed them to expand their range.  During our time in North Carolina, we watched Cliff Swallows go from being a rare bird to become common breeding birds.  

 

Juvenile Cliff Swallow looking out of a nest.  Juveniles
lack the off-white spot on the forehead and have a striped throat.
Davie County, NC.

Cliff Swallow nests are marvelous works of design and construction. Their material of choice is mud,
collected from stream banks or puddles. The nest starts as a glob of mud attached to the cliff (or bridge) and grows one mouthful at time. Then the nest tapers to a spout, making a flask with the entrance pointing down. The swallows lay 3-4 eggs in their new nest and the eggs hatch in about two weeks. Juvenile Cliff Swallows look similar to the adults but with streaks on the throat and they lack the white forehead spot. The nestlings stay in their mud home for another couple of weeks then venture out on their maiden flight.

Adult Cliff Swallow feeding young in the nest.  Davie County, NC

 

A group of Cliff Swallow nests.  A juvenile looks out the nest
on the right while and adult flies in to feed young in another nest.
Davie County, NC.

Cliff Swallows may raise a second brood and stay around the nest colony for the summer.  In September, Cliff Swallows join other birds on their flights to their winter territories in the tropics.  Most migrate through Mexico and Central America headed for to their destination in Northern South America.   We are now in high summer and Cliff Swallow nests are active.  There may be a bridge near you with a nesting colony of Cliff Swallows.  Visit them and you can appreciate the fine construction of the nests and frenetic activity of the birds. 

Cliff Swallows resting and preening on a wire.  Davie County, NC.

We've Been Slimed

Several bright red plasmodia of Raspberry Slime Mold
(Tubifera ferruginosa) on a log.  Rowan County, NC.

This spring was cool and wet, the perfect weather for slime molds.  These amazing creatures are not really Fungi as the mold in their name suggests, but are classified with amoebas.  Slime molds all have an amoeba stage in their life cycles.  There are several groups of microbes that are called slime molds.  The ones we have seen this spring are all giant amoebas.  These monstrous cells, called plasmodia, and can be several inches across.  Plasmodia are often brightly colored and they contain millions of nuclei.  These huge cells crawl across leaf litter or rotting logs and engulf any microorganism in their path.  Eventually the plasmodium produces fruiting bodies that release spores.  These reproductive cells float on the breeze and germinate into new amoebas that then grow into new plasmodia.  Slime molds were the inspiration for the classic 1950s sci fi movie, The Blob.  In this film, a giant plasmodium oozes around a Pennsylvania town consuming the citizenry. 

Close up of Raspberry slime mold showing the red
bumps that resemble a raspberry fruit. Rowan County, NC.

On a drizzly day in May, we were hiking through the woods in a local park.  As we rounded a curve in the trail, we saw brilliant red slime molds on the trunk of a downed tree.  This was a group plasmodia of the Raspberry Slime Molds (Tubifera ferruginosa).   The plasmodia had many small red bumps that mimic the compound fruits of raspberry.  The Raspberry Slime Mold was getting ready to make spores. When we returned two days later, the spore producing sporangia were mature and had turned dark brown. 

Raspberry Slime Mold with white stalks supporting
the developing sporgangia. Rowan County, NC. 

Raspberry Slime mold as the sporangia develop.
Rowan County, NC.

Raspberry Slime Mold with mature, brown sporangia. 
These structures were releasing spores. Rowan County, NC.

Another slime mold we found this spring was a bright white one, Ceratiomyxa fruticulosa, the Coral Slime Mold.  This slime mold was also growing on a log and the delicate, branched white fruiting bodies stood out against the black of the log. 

White plasmodia of Coral Slime Mold (Ceratiomyxa fruticulosa)
on a decaying log. Rowan County, NC. 

Closeup of of Coral Slime Mold plasmodia.
Rowan County, NC. 

Near the Coral Slime Mold, we found another interesting one, Arcyria cinerea.  This slime mold is one of the most common on rotting logs but does not have a common name.   Arcyria cinerea makes delicate, cylindrical, gray sporangia. 

Sporangia of Arcyria cinerea.  Rowan County. NC.

Physarum polycephalum lives in leaf litter or on rotten logs.  This common slime mold is bright yellow and the plasmodium can be a foot across.   Physarum polycephalum is the lab rat of slime molds because its large cell size makes it important in the study cell movement. 

Giant plasmodium of Physarum polycephalum.  Rowan County, NC.

This spring we also saw a beautiful yellow slime mold with an unappealing name, Dog Vomit Slime Mold (Fuligo septica).  The large, bright yellow plasmodium gives this organism another common name, Scrambled Egg Slime.   Dog Vomit Slime Mold often appears on wood chip mulch but may also show up on dead wood of many types.  Dog Vomit Slime Mold has the curious ability to concentrate the metal zinc in its plasmodium.  Russian researchers found Fuligo septica plasmodia contain more than 20 times the environmental concentration of zinc.  The reason for this hyper-accumulation of a toxic metal is unknown, but the yellow pigment of the slime mold helps sequester the zinc and make it less toxic. After crawling around consuming other microbes, the bright yellow plasmodium turns brown and produces spores.  This spore generating stage really does look like dog vomit. 

A migrating plasmodium of Dog Vomit Slime Mold (Fuligo septica).
Rowan County, NC.

Dog Vomit Slime Mold releasing spores.
Rowan County, NC. 

Leaf litter, soil and rotting logs are the natural habitat of countless protozoa, bacteria, fungi and algae.  This biodiversity is mostly invisible to us, but in the case of slime molds their giant cells let us get a glimpse of this world.

Prothonotary Wablers

Prothonotary Warblers (Protonotaria citrea) are small songbirds with a strange name and a spectacular presence in their swamp homes. They are neotropical migrants that return from their wintering grounds in Central America and northern South America to breed in the lowland forests of eastern North America.

A male Prothonotary Warbler (Protonotaria citrea) on its nesting territory.
Davie County, NC.

Church hierarchy has provided names for a number of bird species like Cardinals and Bishops. The unusual name for this delightful bird also has an ecclesiastical origin. The Prothonotary, the First Notary of the Catholic Church, wore yellow vestments while carrying out his duties.

You usually hear a Prothonotary Warbler on its breeding ground before you see one. The Prothonotary song is a loud and emphatic, SWEET-SWEET-SWEET, that the male uses to mark its territory. Then there is a light in the forest. A singing male flies into view. He is a rich yellow color and he does, as the Grateful Dead lyricist Robert Hunter wrote, “glow with the gold of sunshine”. The warbler’s black eye and ebony beak stand out against the golden feathers of the head and neck.  Its wings and tail are blue-gray.

A Prothonotary Warbler bringing nest material to a tree cavity
made by a Downy Woodpecker.  Rowan County, NC. 

Unlike most warblers that make traditional nests, Prothonotaries nest in tree cavities. They use an old woodpecker hole in a dead tree or branch and line the interior of the cavity with twigs, leaves and moss. Prothonotary Warblers will also raise families in nest boxes. They lay 4-6 eggs and in many areas, Prothonotaries can produce two broods per year. Their nest are vulnerable to raccoons, snakes and to Brown-headed Cowbirds (Molothrus ater), a nest parasite.

A Prothonotary Warbler peeking out of its cavity nest.
Rowan County, NC.

A Prothonotary Warbler entering a nest box. Mecklenburg County, NC.
Photo courtesy of Christine McCluskey.

Prothonotary Warblers feed on insects and other invertebrates. One day I saw a Prothonotary catch several dragonflies as they emerged from the old nymph exoskeleton and crawl up on a stick to complete the transformation to the adult stage. After the bird flew off, I found a pile of wings the warbler removed before eating the body of the dragonflies.

As fall comes on, Prothonotary Warblers start to move south. These little birds make long distance flights over water. Some fly right across the Gulf of Mexico to the Yucatan while others hop the islands of the West Indies to South America. Prothonotaries are often found in mangrove forests on their wintering grounds and join in mixed flocks of other small birds for mutual protection.

Prothonotary Warbler.  Rowan County, NC.

The population of Prothonotary Warblers has decreased significantly with more than a 40% decline since the 1960s. This mirrors a similar decrease in numbers experienced by other warblers. One of the factors in this decline is the loss of mangrove swamps in their tropical winter homes. There is some good news. Individuals and conservation groups are putting out Prothonotary Warbler nest boxes.  This  effort has resulted in local population increases in suitable habitat.

Each spring I look forward to the return of Prothonotary Warblers to the swamps in my area.  These golden creatures with their bold songs brighten even the dimmest of days.

April Showers Bring...

A Mayapple (Podophyllum peltatum) plant in April.  This two-leafed plant has
produced a single white flower.  Rowan County, NC.

Mayapples.  These marvelous plants (Podophyllum peltatum) emerge from the ground in early spring like a closed umbrella.  The lobed leaves expand and the umbrella theme continues with the petiole of the leaf in the center.  In fact, another common name of this plant is Umbrella Leaf and the specific name, peltatum, refers to an umbrella-like structure with a stem in the middle.  

Mayapples with newly emerged leaves.  The leaves are umbrella-like, with the
petiole in the center.  Rowan County, NC.

Mayapples grow in large clonal colonies in the understory of eastern forests.  Some Mayapple plants produce a single leaf and others produce paired leaves.  Only the paired leaf plants produce flowers.  The flowers are white with a variable number of petals and produce a yellow fruit, the May Apple. 

A stand of Mayapple plants in the understory of a
deciduous forest.  This stand is probably a clone.  The
genetically identical plants all growing
from a common rhizome.  Rowan County, NC. 

A flower bud of a Mayapple. The single flower emerges from
between the two leaves.  Rowan County, NC.

A young Mayapple flower just opening. Rowan County, NC.

A closeup of a Mayapple flower.  Rowan County, NC. 

A Mayapple plant with its single fruit.  Rowan County, NC.

Mayapples leaves, roots, stems and young fruits contain podophyllotoxin.  If ingested, this naturally occurring poison causes diarrhea, vomiting, excessive salivation and other dire symptoms.  Podophyllotoxin works by interfering with cell division.  This plant-derived toxin is used medically in cancer chemotherapy and it has antiviral properties.  The mature fruit contains lower levels of the toxin and can be eaten in small amounts.  

As the fruits mature, the leaves begin to show yellow blotches.  A fungus, Mayapple Rust (Allodus podophylli), causes these spots.  Fungal spores emerge from the bottom of the infected Mayapple leaves to infect other plants.  The rust is a sign the life cycle of the Mayapple is ending. By late May the fruit is ripe and the plants begin to fade.  Many animals, including Box Turtles, eat the Mayapple fruits.  A turtle that has eaten a Mayapple fruit can carry away the seeds in their digestive tract and deposit them to establish new colonies of this spring favorite. 

The upper side of a Mayapple leaf with Mayapple Rust (Allodus podophylli). 
Infected sections of the leaf turn yellow.  Rowan County, NC.

The underside of a Mayapple leaf infected by Mayapple Rust. 
The dark spots are structures producing the spores that
allow the fungus to infect other plants. Rowan County, NC.

Violets are ...

Purple flowers and bright green leaves are the colors of spring.  Bluets, irises and particularly violets against a green background shout springtime.  Bees are the main pollinators of violets and because the bee visual system is tuned to the ultraviolet and blue part of the spectrum, violets are bee magnets.  A group of large colorful butterflies, the fritillaries, has a different relationship with violets. Fritillaries lay their eggs on violets and their caterpillars develop there, but the adults sip nectar from other flowers. 

A patch of Purple Violet (Viola sororia)
in our lawn, Salisbury, NC

Great Spangled Fritillary (Speyeria cybele) in Rowan County, NC.  This
dramatic butterfly develops on violets.  Here it is feeding on Lantana camara.

Violets are in the genus Viola and have a worldwide distribution with most species found in the temperate regions of the northern hemisphere.  North America boasts about 80 species of violets and while many have flowers with the typical purple color, some species produce blue, white or even yellow flowers.

A unique feature of violets is they make two types of flowers.  One is the large, colorful flower, pollinated by insects we associate with violets.  Botanists term these flower chasmogamous.  The second type of flower violets make are small, they never open, lack petals and self-pollinate.  These small flowers are called cleistogamous.   Chasmogamous and cleistogamous are impressive words derived from Greek.  Chasmogamous means open reproduction.  They are bee pollinated and increase genetic diversity by outcrossing.  Cleistogamous is closed reproduction where the small, closed flowers do not host bees and only pollinate themselves.  This type of reproduction does not increase genetic diversity but is highly efficient.  The cleistogamous flowers produce many more seeds than the chasmogamous. 

Viola sororia showing rhizome with roots, leaves and
both chasmogamous and cleistogamous flowers. 

A common violet in the Southeast is Viola sororia, the Purple Violet.  This plant is a perennial and goes by a number of common names; Meadow Violet, Blue Violet, and most interestingly Lesbian Violet.  This last common name came from the ancient Greek poet Sappho of Lesbos who described her lover wearing violets in her hair.   The Purple Violet makes chasmogamous flowers that are about an inch and a half across and range in color from purple to white.   Purple Violets have an underground stem, the rhizome, that produces the heart shaped leaves, flowers and roots.  The colored, chasmogamous flowers are on long stalks and rise above the level of the leaves.  The closed cleistogamous flowers are pale green and are at ground level or sometimes underground.   Viola sororia readily hybridizes with other species of violets and a number of hybrid forms are recognized.  Purple Violet is a weedy plant and we have large stands in our yard that we do not mow and just enjoy the color.

Closeup view of a Viola sororia chasmogamous flower. 
The purple color attracts its bee pollinators.  

A cleistogamous flower of V. sororia.  These flowers are small, green, close
to ground level and self-pollinated.  

Another view of V. sororia cleistogamous flowers.   

Another common, weedy violet is Viola bicolor, the Field Pansy.  This annual is also a lawn denizen, at least in lawns that are not grass monocultures.  Field Pansy is a small plant with dissected leaves and flowers that range from white to blue.  The flowers have small blue lines and often a yellow center. 

A chasmogamous flower of Viola bicolor.  The purple stripes
on the flower directs insect pollinators to the nectar and pollen.  

Violets have a long history in traditional medicine.  They have been used to treat insomnia, respiratory problems and as an emetic.  I have not used violets to treat medical conditions but enjoy them as the color of spring.

Spring Ephemerals Part 2

Perfoliate Bellwort (Uvularia perfoliata).  A spring ephemeral flowering in

Rowan County, NC in April

The trees are leafing out, the canopy is nearly closed and the understory is greening.  This means the spring ephemeral flowering season is drawing to a close.  Spring ephemerals are small plants that grow on the forest floor and flower early to complete their life cycle in the spring of the year.

A deciduous forest in Rowan County, NC during March.
The canopy is open and the spring ephemerals
are starting to flower,

The same forest in mid-April.  The tree canopy nearly
blocks the sky, the shrub layer is greening up and the light intensity is much lower
than in March.  April means the spring ephemerals are finishing up.  

One of the most visible spring ephemeral in the Southeast is Trillium cuneatum or Little Sweet Betsy.  Trillium cuneatum is a perennial and emerges early in spring bearing three mottled, green leaves and a dark purple, three parted flower.  This flower is pollinated by bees and produces a single purple berry.  Trillium cuneatum is found in the Mountains and Piedmont of the Southeast and extends into Illinois and Pennsylvania.

Trillium cuneatum with is mottled leaves and an unopened flower bud.
Rowan County, NC.

Another view of the plant above showing the
large size of the flower bud.

Trillium cuneatum with open flower.

Windflower (Thalictrum thalictrodes) is a member of the Ranunculus family along with buttercups, hepaticas and columbines.  Windflower flowers are delicate, white and odd.  The flowers lack petals but instead have 5-10 white sepals that play the role of attracting early spring pollinators.   The leaves of Windflower are compound with three leaflets.  Thalictrum thalictrodes grows on the Piedmont and Mountains of North Carolina and throughout the eastern United States.

A Windflower plant (Thalictrum thalictoides) showing its compound leaves
and white flowers with variable numbers of white sepals. Davidson County, NC.

A closeup of a Windflower flower.  Note the multiple sepals and stamens.  Each
stamen has a yellow, pollen-bearing anther.  Davidson County, NC.   

Perfoliate Bellwort (Uvularia perfoliata), found in the Eastern United states and Canada, has pale yellow, bell-shaped flowers.  The genus Uvularia is named for the nodding flowers that resemble the uvula, that pendulous structure at back of the human throat.   The species name perfoliata, refers to the perfoliate leaves of this herb, whose base surrounds the stem. 

Perfoliate Bellwort in flower.  Rowan County, NC.

Perfoliate Bellwort showing its perfoliate leaf, the base of which

surrounds the stem.  Rowan County, NC. 

Spring Beauty (Claytonia virginica) is a beauty.  It has long, grass-like leaves and five-petaled, pink-lined, white flowers.  Like the other plants in this blog, Spring Beauty is found in Eastern North America, flowering early in rich woods.  Spring Beauty has a specialized, underground stem called a corm.  These corms were collected and eaten by Native Americans and taste like chestnuts.  Given their small size, it must have been a lot of work to collect enough Spring Beauty corms for dinner. 

Spring Beauty (Claytonia virginica) in flower.  

Flowers of Spring Beauty.  Each petal has fine pink lines that direct
pollinating insects to the nectar and pollen.  Mecklenburg County, NC.  

Spring is moving on and the spring ephemerals in North Carolina are finishing up.  But, for the last few weeks they have been putting on quite the show. 

A stand of Little Sweet Besty, Trillium cuneatum.