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.