Alder Action

Male catkins of tag alder in late winter

Alders are shrubs or small trees and their distribution includes most of the northern hemisphere.  They are classified in the genus Alnus and are related to birches, hazels and hornbeams. In the southeastern United States, the most common alder is Alnus serrulata, the tag or hazel alder.  

The tag alders grow in swamps, along streams and the edges of lakes.  Tag alders begin to flower in late winter before any leaves open.  Alders have an interesting reproductive system.  They make different male and female flowers, thus they are monoecious with both sexes on the same plant. This is to distinguish them from dioecious plants like willows that have separate male and female plants.  Alnus serrulata produces male flowers in a hanging array called catkins.  Each catkin has dozens of small, yellowish-brown male flowers that have stamens that release pollen.  The flowers of the catkins are dull because alder is wind pollinated and do not have to attract pollinators like insects or birds.  The female flowers are also borne on catkins but these are reddish brown in color and resemble small cones.  The leaves of tag alder emerge in early April and are bright green with serrations along the margin.  Small, winged fruits develop in the female cones and fly through the air to establish new alders in late summer. 

Female catkins (cones) of tag alder in early spring

Female cones from the previous year

Tag alder leaves in early spring

Alders play a role in preventing erosion and stabilize stream banks.  They also have another ecological role in enriching the soil where they grow.  Alders have a symbiotic relationship with a nitrogen-fixing bacterium in the genus Frankia. Like the better-known symbiosis between legumes and their nitrogen-fixing bacteria, alders host colonies of their bacterium in root nodules.  The plant provides sugars and other organic molecules to the bacterium and the bacterium in turn converts nitrogen gas from the atmosphere into ammonia that is usable by the alder.

Look for alders as you walk along the edge of a pond or riverbank.  They have a lot going on. 

The Appearance

My first post to this blog was about the disappearance of birds in the fall as they migrated for points south.  Now with spring the full bloom the birds are returning.  Species we have not seen for months are showing up every day.

Blue-gray Gnatcatcher 

Among the first to arrive in the Piedmont of North Carolina, typically in late March, are the Blue-gray Gnatcatchers (Polioptila caerulea).  These tiny birds are relatives of the Ruby-crowned and Golden-crowned Kinglets that have been with us all winter.  One reason the gnatcatchers get here early is that part of their population has a short migration.  Many Blue-gray Gnatcatchers winter along the southeastern coast including the entire peninsula of Florida.  Others cross the long reaches of water to winter in Central America, Mexico, Cuba and other isles of the West Indies.  The gnatcatchers begin to nest as soon as they arrive, giving their nasal call, snee-snee.  Within a few days, a pair of gnatcatchers can construct of compact nest of plant fibers.  They cover the nest with lichens and spider silk so it looks, for all the world, like a knot on a limb.   A pair of gnatcatchers lay 3-5 eggs that hatch in a week and a half.  Within 2 weeks of hatching, the next generation of gnatcatchers are flying around catching gnats. 

Louisiana Waterthrushes (Parkesia motacilla) arrive early too.  Despite the name these birds are not thrushes but warblers.  They have spots on the breast like a good thrush but are smaller.  Louisiana Waterthrushes are joined a couple of weeks later by their relatives, Northern Waterthrushes.  Northern Waterthrushes (Parkesia noveboraracensis) only stay a short while and migrate further north.  Both species have the spotted breast, an eye line and both bob their tails.  Louisiana Waterthrushes nest near running water and their distinctive song rings out in early spring.

Louisiana Waterthrush 

Prothonotary Warbler

Prothonotary Warblers (Protonotaria citrea) appear around the first week of April.  These denizens of swamp forests glow gold, seemly from an internal light.  With contrasting black eyes and blue wings, these warblers sing their song, SWEET-SWEET-SWEET throughout the day.  Most warblers build their nests of plant material in trees or on the ground, but Prothonotaries use old woodpecker holes to lay their eggs and raise their young.  Once I watched a Prothonotary catch newly emerged dragonflies along the edge of a pond.  The warbler picked off the dragonflies as they crawled from the water onto plant stems.  The Prothonotary pulled off the wings and brought the insect to their hatchlings in an old Downy Woodpecker hole.  Prothonotaries winter in the Neotropics after making the dangerous over water migration in fall.  A few months later, they return to their breeding grounds in North America after another harrowing migratory flight. 

Male Summer Tanager

Tanagers are a large group of birds native to the American tropics.  With more than 200 species, tanagers inhabit a variety of ecosystems ranging from mangrove forest to grasslands above tree line.  Tanagers are among the most brightly colored songbirds.   Some of these tropical beauties make their way to the US and Canada.  In the east, we are privileged to have Summer Tanagers (Piranga rubra) and Scarlet Tanagers (Piranga olivacea) with us for the breeding season.  The males of both species are bright red with the Scarlet Tanager showing black wings and tail.  The females of Summer and Scarlet Tanagers are yellow-green in color and blend perfectly with the leaves of the great trees where they nest.  There are several other species of tanagers in western North America including the Western Tanager (Piranga ludoviciana), Hepatic Tanager (Piranga flava) and Flame-colored Tanager (Piranga bidentata).  This winter and spring a male Western Tanager frequented bird feeders near our home.  Birders from the area came; you might even say they flocked, to see this rare visitor                                                                           from the west. 

Western Tanager in Salisbury, NC during March 2019

Tanager evolution and therefore their taxonomy is complex.  This group has recently undergone a reclassification.  One group of tanagers has been moved to the finch family.  Our tanagers, those that breed in North America, have been reclassified with the cardinals.  Regardless of their taxonomic status, these brilliant birds are a joy to experience, whether in the Andes or North Carolina. 

Small, Green and Easily Overlooked

Mosses are small, green and easily overlooked or mistaken for other plants.  Spanish moss is a flowering plant. Reindeer moss is really a lichen.  Club moss is actually a relative of the ferns.  There are more than 12,000 species of real mosses and they grow on every continent including Antarctica. It is said that moss grows on the north side of trees but don’t count on that to save you if you are lost in the woods. 

A patch of moss in a lawn, Salisbury, NC

Smallness is the key to moss success. Mosses are modern-day echoes of the first primitive plants that colonized the land.  They crawled from the sea, or perhaps a warm little pond, 470 million years ago and covered the land with green fuzz.  The first land animals came in the wake of the primitive moss-like plants.  These early land animals left no fossils but they did leave fossil tunnels in soil similar to what millipedes make today.  

Back to smallness.  There are no 100-foot mosses, not even in the fossil record.  This is because mosses lack xylem and phloem, the vascular tissues of plants that transport water and nutrients.  Mosses stayed small because they have no means to move water to the top of a 100-foot plant. They rely on diffusion to move nutrients about the plant.  Lack of vascular tissue also limits size in another way.  Trees attain their great height because of their woody trunks, and wood is mostly xylem, the water transporting tissue. 

Ceratodon purpureus with
sporophytes growing from the
gametophyte

Mosses lack true roots, stems and leaves.  They have structures that are very leaf-like called phyllids.  Phyllids are usually one cell layer thick, flat, green and carry out photosynthesis.  The moss “stem” is the axis and the root-like structures are called rhizoids.  The rhizoids, axis, and phyllids are all made of cells that have only one copy of each chromosome, and make up the gametophyte generation. The gametophyte generation produces eggs and sperm, the gametes.   

Mosses go through another stage to complete their life cycle. In early spring gametes fuse and the result of fertilization produces the sporophyte.  The sporophyte generation is made of cells with two copies of each chromosome and grows out of the top of the moss.  The sporophyte has a stalk and atop that stalk is the capsule, the spore producing structure.  Since the gametophyte generation produces gametes the sporophyte generation must produce spores.  The spores are microscopic and when released from the capsule float through the air.  If a spore happens to land in a suitable environment, a new moss gametophyte grows.   

The marvelously named Entodon seductrix,
the seductive entodon

The first moss-like plants that came onto land had a dominant gametophyte.  As land plants  evolved the sporophyte generation became more important.  Ferns, conifers and flowering plants all have dominant sporophytes that make vascular tissue.  This allows these vascular plants to become much bigger than mosses. 

So, in the spring look for the sporophytes peeking out of the mosses and know they are completing a life cycle that has been turning since long before vertebrates came onto the land. 

Ceratophyllum purpureus 

Of Skunks and Cabbages

We live just a few miles from the southern-most population of skunk cabbage, Symplocarpus foetidus.  These fascinating plants look like cabbage (kind of) and its leaves and flowers give off a strong odor (the skunky part of the name).  The specific name foetidus comes from Latin and means smelly.  Skunk cabbages live along creeks and in swamps across eastern Canada, the northern US east of the Great Plains and as far south as Tennessee and North Carolina.  On an early spring morning, I hiked up an unnamed branch of Swearing Creek.  As I rounded a bend, dozens of bright green plants were emerging from the creek and its soggy banks.  The flowers were finished but some decaying fruits remains. 

A population of skunk cabbage, Symplocarpus foetidus, in Piedmont North Carolina

Skunk cabbage is one of the earliest flowering plants in its range with the flowers produced in deep winter.   Snow covers the ground in many places when skunk cabbage flowers.  Its most amazing trick is the flowers can melt their way through snow.  Skunk cabbage uses a special thermogenic type of respiration to raise the flower temperature above that of its surroundings, melting snow and giving off its foul odor.  This smell attracts early emerging flies to act as pollinators.  

Skunk cabbage with decaying spathe and spadix

Skunk cabbage emerging from the water

Spathiphyllum with a flower bearing spadix
and the white, leaf-like spathe

Skunk cabbage is in the family Araceae that also includes Spathiphyllum, a familiar houseplant.   The Araceae produce distinct flowering structures; the spadix and the spathe.  The spadix is an inflorescence, a group of flowers that develop into fruits.  The spadix is surrounded by the leaf-like spathe.  The spathe of skunk cabbage is green with purple stripes. The purple color and strong smell resembles rotting flesh and attracts the fly pollinators.  The largest flower in the world, the titan arum, Amorphophallus titanium, is in the same family with a 10-foot flower, purple spathe, a giant spadix and fetid smell. 

I hope to visit the skunk cabbage site again next winter and find flowers melting their way through snow, in full stench.

Winter Decomposers II: The Return of the Fungi

Fruiting bodies of Giraffe spots 
Peniophora albobadia

I am on a mycological kick so I will keep kicking.  Diane and I found a couple more interesting fungi growing on dead sticks recently. 

The first is giraffe spots Peniophora albobadia.  What you see with giraffe spots is really the fruiting body, the spore producing structure, growing tightly appressed to the stick.  Most of the fungus is the hyphae that are rotting the dead wood from the inside.  The fruiting body of this crust fungus is flat and brown with white margins.  This fungus often grows in groups and as the name suggests look like the pattern of spots on giraffes.  Giraffe spots is an important decomposer but is also a pathogen on peaches, nectarines and apricots. 

Giraffe coat pattern

Petr Kratochvil 

(publicdomainpictures.net)

Giraffe spots Peniophora albobadia
detail showing pattern

The second nice fungus was growing on a dead limb of the ornamental plant photinia.  This shelf fungus is a polypore with light and dark rings on the top of the fruiting body.  On the underside of the cap there are many pores (naturally) arranged in a labyrinthine pattern.  The scientific name of this fungus Daedalea quercina is quite apt.  The specific name, quercina, refers to the genus of oak, Quercus.  

Daedalea quercina showing the top of
the fruiting body with alternating light and dark rings

Daedalea quercina showing the underside of the
fruiting body with its labyrinthine pores

Our specimen was not growing on oak but this fungus is common on dead branches of that tree. The genus name Daedalea goes back to Greek mythology, named for Daedalus who built the Labyrinth for King Minos of Crete.  In the Labyrinth was imprisoned the Minotaur, a monster who ate sacrificial Athenian children.  The pores on this fungus, with their twisting chambers and passages could be a maze from which escape is futile. 

Ents, Christmas decorations and a nest: A lichen story

Lichens are fascinating.  Slow growing, pulling nutrients from the air and converting rocks into soil these consummate symbionts are found on all continents, grow from sea level to mountaintops and from the tropics to the arctic.  Their colors range from red and orange to gray-green to bright yellow.  Lichens are a combination of a fungus, and a photosynthetic microbe, either a green alga or a  cyanobacterium (formerly know as blue-green algae). 

Lichens on a sea cliff in Wales

Lichens are classified according to the fungus they contain rather than the by their photosynthetic partner.  The body of the lichen, the thallus, is made of fungal filaments called hyphae.  Within the thallus is the photosynthetic alga or cyanobacterium.  The photosynthetic cell produces sugars for the fungus and the fungus provides water and nutrients to the alga.   A lichen’s growth form is different from either the fungus or the alga when they live independent of each other. 

Lichens can live in very harsh environments and are among the first colonizers of bare rock.  Lichens secrete acids that begin the chemical weathering of rock to produce soil.  Lichens also commonly grow on trees trunks and branches taking water from rain and dew and inorganic nutrients from dust and bird droppings.  Lichens are very slow growing, a few millimeters per year in some cases, because optimal growth conditions may only occur a few hours a day.  In the high arctic lichens grow on the ground and are grazed by large mammals.  This is why one of the arctic lichens has the common name reindeer moss. 

Despite living in forbidding environments lichens are very susceptible to air pollution, particularly sulfur dioxide.   In urban Washington, DC parks, the lichen diversity is much lower than in parks in the surrounding area.  This difference in lichen distribution is due to the air pollution in town.

Lichens exhibit a number of different growth forms.  Some grow as a thin layer tightly appressed to rock, cemetery headstone or tree trunk.  These are the crustose lichens since they form a crust on their substrate. 

 

A crustose lichens in south Florida

Foliose lichens have flat, leaf-like thalli whose edges are not attached to the surface on which they grow. 

 

Parmotrema sp. a foliose lichen in North Carolina

Fruticose lichens are three-dimensional and branched.  Fruticose lichens resemble little trees or bushes and are used by model railroaders to add tiny trees to their displays.  Treebeard, the Ent in J.R.R. Tolkein’s The Lord of the Rings, had a beard of fruticose lichens

Cryptothecia rubrocincta or Christmas lichen is one of the most beautiful of all the lichens.  It grows throughout tropical America and extends its range into the subtropical regions of the United States.  You can find it growing near the coast from Texas to Florida and into North Carolina.  The Christmas lichen’s range tracks very closely the distribution of the cabbage palmetto.  This crustose lichen stands out on the tree trunks that support it because it is bright red.  The color of this lichen varies from red and pink to white and looks much like a Christmas decoration on the tree.  Two chemicals, beta-carotene and chiodectonic acid cause this lichen’s red color.  The algal symbiont produces the pigment beta-carotene and chiodectonic acid is produced by the fungus.  Both these compounds probably protect the lichen from ultraviolet damage and other environmental stresses. 

 

Cryptothecia rubrocinata, Christmas lichen in a Florida cypress swamp

Members of the foliose lichen genus Usnea is widespread and grows on tree trunks and small branches.  Usnea is gray-green in color and resembles small plants of Spanish moss.  Usnea strigosa has reproductive structures found on fungi that are not lichenized.  These flattened cups (apothecia) produce spores and are typical of cup fungi.  The apothecia release spores that germinate and the fungal hyphae must find their particular species of alga to reestablish the lichen symbiosis.

Usnea strigosa, a fruticose lichen with apothecia in North Carolina

 The scientific name of Spanish moss is Tillandsia usneoides, so-named for its resemblance to the lichen.  The Northern Parula is a warbler that winters in Central America and on Caribbean islands. In spring, Parulas fly to eastern North America where they nest.  On the coastal plain of the southeastern United States, the Northern Parulas make their nests of Spanish moss while further north they use Usnea for nest material.  Even this warbler notes the resemblance between the Usnea and Spanish moss.    

Winter Decomposers

Fungi make their living a variety of ways.  Some are parasites taking nutrients from living organisms.  Some are symbionts associated with the roots of plants that transfer inorganic nutrients to the plant in exchange for sugar and other organic molecules.  And some fungi decompose formerly living material.  These decomposers mainly break down dead plant parts. Without the decomposers, a walk in the woods would be wading through a sea of dropped leaves, a tangle of downed branches and impassable barriers of dead tree trunks.   We usually don’t see these vital components of the ecosystem except when they make their reproductive structures called fruiting bodies or more familiarly, mushrooms.  Most of the fungal biomass is in microscopic threads of cells called hyphae.  The hyphae of the decomposers growth throughout the dead plant parts and release enzymes that break down highly resistant plant polymers like cellulose and lignin.  The fungus then absorbs the breakdown products of these polymers and the plant parts are recycled.  Winter is not typically a good time for finding mushrooms in this area but the decomposers are an exception. 

Turkey tail fungus, Trametes versicolor, on a rotting log

On some recent hikes, we found several of these winter decomposers. One prominent fungus on dead tree trunks is the turkey tail (Trametes versicolor).  The flat caps of the turkey tail grow in large groups on dead trees.  They are quite striking with alternating bands of varying shades of brown, gray and white that resembles the tail of a turkey.  On the underside of the cap are small oval pores that produce the spores of the fungus. These pore-bearing fungi are Polypores, classified in the family Polyporaceae. The spores float through the air and if lucky enough to land on a dead tree, can establish another colony of turkey tail fungus. 

Fruiting bodies of Poronidulus conchifer

Small white mushrooms growing on small dead branches is Poronidulus conchifer another Polypore. The pores are found on the lower side of the fruiting body.  This fungus is closely related to the turkey tail.  The scientific name quite descriptive. The genus, Poronidulus, is from the Latin meaning “little nest with pores”.  When the fruiting body is small it is curled up and look like little bird's nests.  Since it is a The species name, conchifer, is Latin for “conch bearing” because the larger fruiting bodies look very shell-like. 

A common large mushrooms growing on downed logs and on dying live trees is the oyster mushroom Pleurotus ostreatus. This fungus is has a worldwide distribution and is a major decomposer of wood.  It is also a choice, edible mushroom.  The whitish caps of the fruiting body resemble oysters and that gives it both its common name and the species name (ostreatus is from Latin for oyster).  The fruiting body usually grows in groups on a tree trunk or log.  The underside of the mushroom bears spore-producing gills typical of members of the order Agaricales, the gilled mushrooms.  Oyster mushrooms make their living decomposing wood but have a more ominous source of nutrients.  Pleurotus ostreatus is also a carnivore.  Hyphae of the oyster mushroom produce droplets of a toxic protein that paralyzes nematodes found in and on the rotting wood.  Oyster mushroom hyphae then invade the body of the paralyzed nematode and consume the unfortunate worm from the inside. 

 

Oyster mushroom (Pleurotus ostreatus) showing spore-producing gills

Oyster mushroom on log with their typical oyster shape

Even in winter, the process of decomposition goes on, carried out by a group of fascinating fungi.