The Shape of Leaves

 

Wild Coffee (Psychotria nervosa), a native of Florida, has simple leaves. 
Palm Beach County, Florida. 

As leaves emerged this spring, I was fascinated by the variety of their shapes.  Leaves are large and small, wide and narrow, simple and compound, and more. With spring light streaming through them, these leaves glow with a profusion of greens and dazzle with their forms.  

Botanists have a welter of terms to describe the shape of leaves.  The flat part of the leaf is the blade. It usually has a large surface area for carrying out photosynthesis.  The blade is connected to the stem by the petiole.  At the point where the petiole emerges, there is a bud that has the potential to grow into a new branch. 

The simple leaf of American Basswood (Tilia americana)
showing the blade and petiole.
Rowan County, North Carolina.   

Simple leaves are, of course, the simplest, with a blade and a petiole.  But even simple leaves show astonishing variation.  For example, simple leaves may have smooth margins, or they can be edged with teeth.  

American Beech (Fagus grandifolia) trees have simple
leaves with toothed margins. 
Rowan County, North Carolina. 

Some simple leaves have lobes.  Many species of Maple (Acer sp.), American Sycamore (Platanus occidentalis), Sweetgum (Liquidambar styraciflua) and a variety of Oaks (Quercus sp.) have lobed leaves.  

The lobed leaves of Red Maple (Acer rubra).
Rowan County, North Carolina. 

Silver Maple (Acer saccharinum) with lobed leaves.
Rowan County, North Carolina. 

Lobed leaves of American Sycamore (Platanus occidentalis).
Rowan County, North Carolina.  

Sweetgum (Liquidambar styracifula) is another 
tree with lobed leaves. 
Rowan County, North Carolina. 

White Oak (Quercus alba) leaves
have large rounded lobes.
Rowan County, North Carolina.  

Swamp Chestnut Oak (Quercus michauxii)
leaves have small rounded lobes. 
Rowan County, North Carolina. 

Northern Red Oak (Quercus rubra) has pointed lobes.
Rowan County, North Carolina. 

Red Mulberry (Morus rubra) can have both lobed and unlobed leaves, even on the same tree.  Sassafras (Sassafras albidium) leaves can have no lobes, two lobes or three lobes.  

An unlobed Red Mulberry (Morus rubra) leaf.
Rowan County, North Carolina. 

A lobed Red Mulberry leaf.
Rowan County, North Carolina. 

An unlobed Sassafras (Sassafras albidum) leaf.
Rowan County, North Carolina. 

A two-lobed Sassafras leaf.
Rowan County, North Carolina. 

A three-lobed Sassafras leaf.  All these Sassafras
leaves were on the same tree.  
Rowan County, North Carolina. 

Tulip Poplar (Liriodendron tulipifera) leaves have a unique lobed pattern with two lobes at the broad tip and two to four lobes near the petiole.  

The distinctive lobed leaves of
Tulip Poplar (Liriodendron tulipifera).
Rowan County, North Carolina. 

Some leaves, like those of Yarrow (Achillea millefolium), have very deep lobes.  These leaves are called dissected. 

A dissected leaf of Yarrow (Achillea millefolium).
Rowan County, North Carolina. 

Compound leaves have a petiole with multiple leaflets.  They come in two forms, palmately compound and pinnately compound.  Palmately compound leaves, like Saw Palmetto (Serenoa repens) and Virginia Creeper (Parthenocissus quinquefolia), have the leaflets emerging from a single point at the end of the petiole.  This leaf type resembles fingers emerging from the palm of a hand.  The palmate arrangement gave palm trees their name. 

Saw Palmetto (Serenoa repens) has palmately compound leaves.
Palm Beach County, Florida. 

A palmately compound leaf of
Virginia Creeper (Parthenocissus quinquefolia).
Rowan County, North Carolina. 

Pinnately compound leaves have leaflets emerging along the length of the central vein.  American Ash (Fraxinus americana), Pignut Hickory (Carya glabra) and Smooth Sumac (Rhus glabra) all have pinnately compound leaves. One species of maple found in the Southeast, Boxelder (Acer negundo), has pinnately compound leaves rather than lobed leaves.  

Pinnately compound leaves of
American Ash (Fraxinus americana).
Rowan County, North Carolina.  

A Pignut Hickory (Carya glabra) pinnately
compound leaf seen from below.
Rowan County, North Carolina. 

Smooth Sumac (Rhus glabra) has pinnately compound leaves.
Rowan County, North Carolina. 

Unlike most maples, Boxelder (Acer negundo)
has pinnately compound leaves. 
Rowan County, North Carolina. 

Sedges (Carex sp.) and Rushes (Juncus sp.) have long, narrow leaves that botanists call linear.  

Linear leaves of Gray's Sedge (Carex grayii).
Davidson County, North Carolina. 

Common Rush (Juncus effusus)
has round, linear leaves. 
Rowan County, North Carolina. 

Some plants have heart-shaped leaves. The technical term for this leaf type is cordate.  Eastern Redbud (Cercis canadensis) and Air Potato (Dioscorea bulbifera) both have cordate leaves. 

 

Redbud (Cercis canadensis)
has heart-shaped or cordate leaves.
Rowan County, North Carolina. 

Dioscorea bulbifera or Air Potato has cordate leaves.
This native of Africa and Asia is an invasive
species in the Southeastern United States.  
Palm Beach County, Florida. 

A peltate leaf resembles an umbrella, with the petiole attached to the center of the blade.  Mayapple (Podophyllum peltatum) has peltate leaves that are palmately lobed.  The specific name for Mayapple refers to the leaf shape.

A peltate leaf of Mayapple (Podophyllum peltatum) from above.
Rowan County, North Carolina. 

A peltate leaf of Mayapple from below.  
Rowan County, North Carolina. 

A perfoliate leaf lacks a petiole and the base of the blade surrounds the stem.  This pattern is seen in the early spring wildflower, Perfoliate Bellwort (Uvularia perfoliata).   As with Mayapple, the specific name refers to the leaf type. 

A perfoliate leaf of Perfoliate Bellwort (Uvularia perfoliata).
Rowan County, North Carolina. 

Besides being part of a dazzling botanical show, the shape of leaves is useful and even essential for plant identification.  Generations of plant taxonomy students and others haven been intimidated by and mastered the terms that describe leaves.  This is part of a journey to learn the plants around us. 

Florida: Natives, Invasives and Visitors

 

A Wood Stork (Mycteria americana) carrying nest material.
Wakodahatchee Wetlands, Palm Beach County, Florida. 

We went to South Florida this April and I was struck by how many new animals have taken up residence since I left for college.  Most of the native species are still present but new, exotic and sometimes invasive species have experienced explosive growth.  

American Alligators (Alligator mississippiensis) are decidedly native.  They have prowled what is now Florida for millions of years.  These reptiles can reach truly titanic size; 15 feet in length and weight of up to 1000 pounds.  American Alligators are carnivores and they feed on a wide range of prey; from snails and snakes to fish and frogs to turtles and even cats and dogs.  Diane and I were hiking in a wetland preserve and someone said, “That gator is carrying something big in its mouth”.  It was indeed.  A ten-foot alligator was hauling a dead eight-foot alligator across a pond.  We don’t know how the smaller gator perished, but cannibalism is well documented in American Alligators. 

 

An American Alligator (Alligator mississippiensis)
 hauling a dead gator across a pond.
Wakodahatchee Wetlands, Palm Beach County, Florida. 

One of the first exotic reptiles to arrive in Florida was the Brown Anole (Anolis sageri).  This resident of the Bahamas and West Indies probably reached the Florida Keys in the late 1800s, stowing away on cargo ships.  By the 1970s the Brown Anole had reached Miami then exploded across the Southeast. They are invasive and can outcompete native species like Carolina Anoles (Anolis carolinensis).  Brown Anoles are now found from Georgia to Texas and even in Southern California.  Males have an extendible orange dewlap they use to attract females and scare off rivals.  We happened upon a male Brown Anole that was flashing his colorful throat patch on a tree branch.  A smaller female came running up the branch and they commenced mating.  Another generation of the exotic Brown Anole is coming. 

 

Brown Anoles (Anolis sageri) mating.
Wakodahatchee Wetlands, Palm Beach County, Florida. 

It was breeding season for birds in Florida too. Native wading and water birds were nesting, and baby birds were in abundance.  Wood Storks (Mycteria americana) are black and white giants.  Standing over three feet tall, they build haphazard stick nests and raise ungainly chicks.  The young Wood Storks were still in the nest and covered with white down.  Their first flight feathers were just poking through, and they were exercising their wings in preparation for life in the air. 

 

An adult Wood Stork in its nest tree. 
Wakodahatchee Wetlands, Palm Beach County, Florida.

Juvenile Wood Storks in their nest.
Wakodahatchee Wetlands, Palm Beach County, Florida.

Anhingas (Anhinga anhinga) had babies in the nest too.  These birds have a long, thin neck and a sharp beak they use to spear fish.  Anhingas swim with their body submerged and their neck above water giving them the common name Snakebird.  The sight of adult Anhingas feeding their young was impressive.  The juvenile Anhingas shoving their dagger-like beaks into the throat of their parent was harrowing.  So much could have gone wrong, but it didn’t.   

Video of  an Anhinga (Anhinga anhinga).

Green Cay Wetlands, Palm Beach County, Florida. 

 

Adult Anhinga feeding young.
Green Cay Wetlands, Palm Beach County, Florida. 

Common Gallinules (Gallinula galeata) are native species in the Rail family (Rallidae).  They had babies too.  Young Common Gallinules do not hang around the nest long after hatching.  They quickly begin walking across floating vegetation and fending for themselves.  These juvenile birds were fluffy black balls of feathers with red beaks and incredibly long toes. 

An adult Common Gallinule (Gallinula galeata).
Green Cay Wetlands, Palm Beach County, Florida. 

A fluffy juvenile Common Gallinule.
Wakodahatchee Wetlands, Palm Beach County, Florida. 

The Gray-headed Swamphen (Porphyrio poliocephalus) is also a member of the Rallidae.  This large, iridescent purple marsh bird is native to Asia and escaped from captivity in the aftermath of Hurricane Andrew in 1992.  It is now found in many wetlands of peninsular Florida where it competes with native rails.  We watched as a Gray-headed Swamphen walked through a marsh, snapping off plant stems with its strong beak, grasping the vegetation with its feet and eating it. 

A Gray-headed Swamphen (Porphyrio poliocephalus)
walking through the marsh. 
Wakodahatchee Wetlands, Palm Beach  County, Florida. 

A Gray-headed Swamphen holding a Rush (Juncus sp.)
 in its foot while it eats. 
Green Cay Wetlands, Palm Beach County Florida. 

A Bahama Mockingbird (Mimus gundlachii) was the most interesting non-native bird we saw on this trip.  This bird’s normal range is the Bahamas, Turks and Caicos, Cuba and Jamaica.  Bahama Mockingbirds are larger than the Northern Mockingbirds (Mimus polyglottos) that are native to Florida.  They also lack the white wing patches and white outer tail feathers of the Northern Mockingbird.  Bahama Mockingbirds are rare but regular visitors to Florida. This particular bird was hanging around the campground of Jetty Park at Port Canaveral.  The Bahama Mockingbird was singing and chasing Northern Mockingbirds within sight of the giant cruise ships that take tourists to its homeland.  This Bahama Mockingbird was a visitor but  probably did not ride a cruise ship to Florida.  It may have been blown to Florida by a storm or just wandered across the water. 

 

A Bahama Mockingbird (Mimus gundlachii))
singing in Jetty Park.
Brevard County, Florida.

I think the most spectacular native bird in Florida is the Painted Bunting (Passerina ciris).  The males of this small songbird are kaleidoscopic in color.  They have a blue head and wings, red breast and rump, and a green back.  The females are more sedately hued, sporting a uniform green color.  These brilliant little creatures breed from the Southeast to the southern plains. Painted Buntings winter in south Florida, the West Indies and Central America.  We found several male and female Painted Buntings at a wetland preserve in Palm Beach County, Florida where they winter and pass through on migration. 

 

A male Painted Bunting (Passerina ciris) singing his song.
Green Cay Wetlands, Palm Beach County, Florida. 

Florida is a magnet for people.  Americans and Canadians flock there in winter for relief from the cold.  People from the Caribbean and Latin America arrive daily seeking a better life.  It is no wonder that wildlife from many parts of the world are also mixing with the native species. 

Lycopodium

 

Dendrolycopodium obscurum (Common Tree Club Moss).
A Lycopodium growing in
Rowan County, North Carolina. 

Lycopodium, or club moss, is not a moss at all but a seedless vascular plant. It belongs to an ancient lineage with its origin in the Devonian Period, over 400 million years ago.  Lycopodium was an early land plant and predated the dinosaurs.  Today’s club mosses are small plants but during the Carboniferous Period some Lycopodium relatives were giant trees. Coal deposits in the Appalachian Mountains contain the remains of Lycopodium that reached heights of over 100 feet.  

Lycopodium reproduces by spores made in sporangia that are shaped like clubs (thus the name club moss) and extend above the branched stems.  These stems bear tiny leaves that carry out photosynthesis.  

The genus Lycopodium formerly had 10 species in the Carolinas.  New research has broken that genus up into 7 genera and about 13 species.  I will use the name Lycopodium to refer to this group but use the currently accepted scientific name for each species in the blog. 

 

Dendrolycopodium obscurum with sporangia.
Rowan County, North Carolina. 

Dendrolycopodium obscurum, Common Tree Club Moss, is a small plant of the forest understory.  It has horizontally spreading branches that resemble tiny trees.  The upright plants we see are produced from an underground stem, a rhizome. Common Tree Club Moss is often seen in large stands or in a line all coming from a rhizome.   

 

A line of Dendrolycopodium obscuru from an underground rhizome. 
Rowan County, North Carolina. 

Lycopodiella alopecuroides, Foxtail Club Moss, grows along the ground with branching stems. This species grows in the wet, sandy soil of pine savannas on the Coastal Plain of the Carolinas. 

 

Lycopodiella alopecuroides, Foxtail Club Moss.
Wake County, North Carolina.  

Foxtail Club Moss with branching stems.
Wake County, North Carolina. 

Lycopodium reproduces by spores. These spores have interesting characteristics and some bizarre uses.  The spores are tiny, about 35 micrometers in diameter, and easily float on the air.  Plants release spores that are carried on the breeze, settle to the ground and establish new plants.   But if large numbers of Lycopodium spores are lofted into the air, they are highly flammable and even explosive.  The spores have a high wax content and a huge surface area.  This allows them to rapidly burn.  Lycopodium spores were used in the earliest flash photography.  Nineteenth century photographers would hold up a T-shaped tray filled with spores, squeeze a bulb to shoot the spores into the air and ignite them, giving a brief but brilliant flash to illuminate their subject.  Lycopodium spores have been used to produce theatrical stage flames and explosions.  In fact, Lycopodium spores are commonly called Dragon Breath by magicians who use it in their acts.  They were also used in Native American religious ceremonies. 

Danish-American photographer Jacob Riis using flash powder.
http://hspvaragtime.weebly.com/home/jacob-riis 

Video of flaming Lycopodium spores.

Rowan County, North Carolina. 

Lycopodium is a fascinating member of our flora.  The ancestors of these humble little plants were massive trees and their remains make up much of the coal we continue to burn and warm the planet.  When you see Lycopodium, think that long ago, it fed dinosaurs. 

A large stand of Dendrolycopodium obscurum.
Rowan County, North Carolina. 

Warblers Part 2

 

 Western Palm Warbler (Setophaga palmarum) wintering in south Florida.
Palm Beach County, Florida. 

The American wood warblers, the Parulidae, are gems of the bird world.   When they return from the tropics in spring, their dazzling colors and brilliant songs light up the woods.  This blog continues with some warblers that breed in our area, others that pass through on migration and even an uncommon winter resident.  

A male Hooded Warbler (Setophaga citrina).
This bird stopped on a tiny island in the Gulf of Mexico
 to rest and drink at a pool during migration. 
Dry Tortugas National Park, Florida. 

Hooded Warblers (Setophaga citrina) are bright yellow on the face and breast.  Males have a black hood and females have a paler version of that hood.  They breed in the forests of the eastern United States and winter in south Florida and the American tropics 

 

A male Prairie Warbler (Setophaga discolor) on McDowell Prairie.
Mecklenburg County, North Carolina.  

Prairie Warblers (Setophaga discolor) are small warblers that nest in scrubby fields and forest edges in the eastern United States.  Prairies are yellow with a yellow semi-circle under the eyes and black streaks on the face and side.  These warblers often wag their tails as they hunt their insect prey.

 

A male Chestnut-sided Warbler (Setophaga pensylvanica)
on his breeding territory.
Ashe County, North Carolina. 

Chestnut-sided Warblers (Setophaga pensylvanica) pass through the Piedmont on migration from their wintering grounds in Central America.  They breed from the southern Appalachians to the forests of the northeast and Midwest.  In the mating season, male Chestnut-sided Warblers have a greenish-yellow crown, a black and white face, white breast and belly with a chestnut streak down each side.  Their song is friendly rendition of “Pleased, pleased, pleased to meetcha”.   

 

 A Yellow Palm Warbler on migration.
Mecklenburg County, North Carolina. 

Palm Warblers (Setphaga palmarum) only spend part of their year where palms live.  In summer they breed in the boreal forest and in winter they stay near the coast of the southeastern United States, islands of the Caribbean, Central America and a small population along the Pacific coast of the US.  The wintering range of Palm Warblers is moving north with climate change.  Palm Warblers have a rufous crown, yellow under the tail and brown streaks on the breast.  Palm Warblers bob their tails as they feed in bushes, low trees and on the ground.  

A Western Palm Warbler in winter.
Palm Beach County, Florida.  

There are two subspecies of Palm Warblers. The Western Palm Warbler is the duller of the two and breeds west of James Bay in Canada.  Western Palm Warblers migrate west of the Appalachian Mountains and many winter in the southeast while others move to the tropics.  The second subspecies, the Yellow Palm Warbler, breeds east of the James Bay, migrates east of the Appalachian Mountains, winters along the Gulf Coast and is bright yellow.    

 

A male Cape May Warbler (Setophaga tigrina) on migration.
Rowan County, North Carolina. 

Another warbler that breeds in the far north is the Cape May Warbler (Setophaga tigrina).  These brilliantly colored warblers have yellow on the face, throat and breast.  Cape Mays have an orange cheek patch and black streaks on the breast.  This warbler’s name comes from Cape May, New Jersey where it was first collected on its migration.  Cape May Warblers spend the winter in the West Indies and Central America. 

Canada Warbler (Cardellina canadensis) in fall.
Henderson County, North Carolina. 

Canada Warblers (Cardellina canadensis) do breed in Canada but also in the northeastern and upper Midwest of the US.  They also nest at higher altitudes of the Appalachian chain as far south as Georgia.  Canada Warblers winter in northern South America after the long and dangerous flight over the Gulf of Mexico and Caribbean Sea.  Canada Warblers are gray on the back and wings with a yellow throat and breast set off with a black necklace of streaks. 

 

Tennessee Warbler (Leiothlypis peregrina) on fall migration.
Rowan County, North Carolina. 

Another geographically named warbler is the Tennessee Warbler (Leiothlypis peregrina).  But these warblers only pass through that state whose name they bear on their way to breed.  They inhabit the same northern forests that host Canada Warblers, Cape May Warblers and Palm Warblers.  Tennessee Warblers spend the winter in Central and South America.  They are rather plain birds with a greenish back and wings, gray breast and a black eyeline.   

An Orange-crowned Warbler (Leiothlypis celata) wintering along the
 South Carolina coast. This birds shows a faint orange crown.
Myrtle Beach State Park, South Carolina.

Orange-crowned Warblers (Leiothlypis celata) are called the bird with no field marks.  They are very plain with an olive-yellow body, a faint eyeline and an orange crown that is seldom seen.   Orange- crowned Warblers nest from the Canadian Maritimes west to Alaska and down the Rocky Mountains as far south as Arizona and New Mexico.  They spend their winters in the southern United States, Mexico and Central America.

 

A first-year female Kirtland's Warbler (Setophaga kirtlandii) making
a brief stop in North Carolina on the way to the Bahamas.
Chatham County, North Carolina. 

The rarest of the warblers is the Kirtland’s Warbler (Setophaga kirtlandii).  Kirtland's are long-legged warblers with a broken white eye ring and a yellow breast and belly with bold black stripes. These warblers were nearly extinct by the late 20^th century, but conservation efforts brought them back from the brink.  Historically, Kirtland’s warblers were found throughout the pine forests of the upper Midwest.  They inhabit young pine stands but their habitat was drastically reduced in the 19^th and 20^th centuries by logging and wildfire suppression.  In the late 20^th century the range of Kirtland’s Warblers was reduced to a few counties in the Lower Peninsula of Michigan.  In 1974 researchers found only 167 singing males and it was declared endangered.  The Endangered Species Act provided funding for habitat improvement and reduction of Brown-headed Cowbird (Molothrus ater) populations.  Brown-headed Cowbirds are nest parasites that lay their eggs in the nests of other birds and dramatically reduce the reproduction of the parasitized species.  Kirtland’s Warblers are particularly susceptible to cowbird parasitism.  Through this extensive conservation effort the Kirtland’s Warbler population has grown to over 5000 and the bird has spread to the Upper Peninsula of Michigan, Wisconsin and Ontario.  The population success led the Kirtland’s Warbler to be removed from the Endangered Species List. Kirtland’s Warblers do not spend their entire year in Michigan.  After breeding the birds fly from the Midwest and Canada to the Bahamas.  Occasionally a Kirtland’s Warbler stops in North Carolina to refuel.  When that happens dozens, nay hundreds of birders turn out to get a look at this rarest of the warblers. 

Kirtland's Warbler.
Chatham County, North Carolina.

Despite the success of the Kirtland’s Warbler recovery, warblers in general are in trouble.  Nearly all the warblers discussed in this blog have seen a decrease in population over the last several decades.  There are many reasons for this decline.  Habitat loss and fragmentation of breeding grounds, migration routes and wintering areas all play a role.  Decline in insect populations due to pesticide use and farming practices have drastically reduced the warbler food supply.  Rachel Carson made an ominous prediction in her 1962 book Silent Spring.  She asked us to imagine a spring without the sound of bird song.  Her concern was DDT.  That pesticide was banned in the United States, but it is still used in South America. We have others poisons that took DDTs place in the US, so Carson’s fear is still with us.  I do not want to contemplate a silent spring. But there are small steps we can take.  Limiting pesticide use and using native plants for landscaping supports insect populations that feed the warblers.