Advice from a Caterpillar

While Alice was adventuring in Wonderland, she met a hookah-smoking caterpillar who asked her unpleasant questions and gave her advice.  The caterpillars we run into can give us advice too. 

Monarch Butterflies (Danaus plexipus) feeding on Aster sp. in the
North Carolina mountains

Two common butterflies in the Southeastern United States advise their predators, and us, how dangerous they are.  Monarch Butterflies (Danaus plexipus) are the most charismatic of our butterflies.  They are large, brightly colored and undertake epic migrations from Mexico to Canada and back.  If you plant milkweed in your garden you will probably have Monarchs.  They lay their eggs on the milkweed (Asclepius sp.) leaves.  

Butterfly Weed (Asclepius tuberosa), a species of
Milkweed

The eggs hatch into caterpillars with alternating white, yellow and black stripes.  Monarch caterpillars are not trying to hide.  That is because the milkweed upon which they feed is laced with cardiac glycosides, a potent toxin.  

A caterpillar of the Monarch Butterfly
on Tropical Milkweed (Asclepius curassavica)

Cardiac glycosides, as the name suggests, interferes with heart function that can result in heart failure. Cardiac glycosides also interfere with the digestive tract and muscular system of mammals that ingest them.  Not only that, these molecules taste bad.  The target of cardiac glycoside is a protein pump found in the membranes of all animal cells called the sodium-potassium ATPase.  This large protein maintains the proper balance of sodium and potassium ions in cells.  This is particularly important in muscle and nerve cells.  Monarch caterpillars take in the toxin when they eat milkweed leaves and store it in their bodies.  This makes them less palatable to predators like birds or mice.  The adult Monarchs retain cardiac glycosides after metamorphosis and this protects them from their bird predators.  A good question is; Why don’t the cardiac glycosides kill the monarchs?  It turns out the Monarchs carry a mutated version of the gene for the sodium-potassium ATPase that imparts  resistance to the effects of cardiac glycoside.  So the caterpillars can eat toxic milkweed with impunity, retain the toxin, advertise their toxicity with bright colors and patterns and pass this protection on to the adults. 

A Gulf Fritillary butterfly feeding on Lantana camara.

Another caterpillar giving advice is that of the Gulf Fritillary (Agralus vanilla).  The Gulf Fritillary butterfly, like the Monarch is large with a distinctive pattern of vivid colors.  When seen from above the Gulf Fritillary butterfly is bright orange with bold black spots.  The underside of the butterfly wings are brown and orange with large white spots.  

A Gulf Fritillary seen from below showing large white
spots on an orange and brown background.

Gulf Fritillaries lay their eggs on leaves of Passionflower vines.  The caterpillars hatch and eat the Passionflower leaves. Passionfllowers have chemical defense molecules called cyanogenic glycosides that protect the plant by releasing cyanide.  When a herbivore eats a Passionflower leaf they are poisoned by the cyanogenic glycosides.  But even cyanide cannot deter Gulf Fritillary larvae from eating the leaves.  The caterpillars are bright orange with black spines as if they are daring a bird to eat them.  Like the Monarch, its caterpillar is conspicuous and downright threatening.

Yellow Passionflower (Passiflora lutea) a host plant for
Gulf Fritillaries

Gulf Fritillary caterpillar on Passaflora sp.

Both the caterpillar and butterfly are protected by toxins from the Passionflower.  The adult butterfly also releases noxious chemicals from a gland in the abdomen to further deter predators.    

As a rule, boldly colored insects are toxic and should not be eaten.  I knew a young man that wanted to taste everything he could in the woods.  One day he found a Lady Bug and popped it in his mouth.  He immediately spit it out and spent the next half hour trying to get the horrible taste from his mouth.  The Lady Bug, with its red color and black spots was giving advice.  So are some of the caterpillars. 

An Asian Lady Beetle (Harmonia axyridis) aka Lady Bug
warning us not to eat it.

Basal Angiosperms II

 I wrote earlier this year about a group of plants called basal angiosperms.  These are flowering plants that branched off the evolutionary line that led to the eudicots and monocots.  Basal angiosperms have some characteristics of both monocots, like flower parts in multiples of three, and eudicots, with net veined leaves. 

Waterlilies are basal angiosperms classified in the family Nyphaeacea and grow on all continents except Antarctica.  These familiar plants grow in lakes, ponds and slow-moving streams.  They have floating leaves and brightly colored flowers that emerge from the water.  The largest waterlily in the world is from South America.  This waterlily, Victoria amazonica, has leaves that are ten feet in diameter and can support the weight of a person.  A famous nineteenth century lithograph shows young Annie Paxton standing on a leaf of V. amazonica at the English estate Chatsworth.  Annie’s father, Joseph Paxton, was the head gardener at Chatsworth and the first to get V. amazonica to flower in England.  Paxton noted the ribbed supports on the underside of the leaves of V. amazonica and used these as inspiration to design a large greenhouse at Chatsworth.  Later Paxton became the lead architect of the Crystal Palace that housed the Great Exhibition of London in 1851. 

Annie Paxton standing on a Victoria amazonica leaf at the
English estate of Chatsworth in 1849.
https://en.wikipedia.org/wiki/Victoria_amazonica
 

We could not visit the Amazon Basin to see these lilies but Fairchild Tropical Botanic Garden in Miami, Florida has Victoria sp. growing in a pond.  The Miami Victorias are not as large as those growing in the Amazon but the Florida plants sport 2-3 foot leaves that have the characteristic upturned edges.

Victoria sp leaves at Fairchild Tropical Botanic Garden
Miami, Fl

Two common waterlilies in the Southeast are the alliterative Nymphaea and Nuphar.  One is Nymphaea odorata or the fragrant waterlily.  The scientific name of the fragrant waterlily is a wealth of information.  The genus Nymphaea gets its name from the nymphs of Greek mythology.  These minor female deities were associated with natural sites, particularly water.  The species name, odorata, tells that the flowers are fragrant and help attract its beetle pollinators. Fragrant waterlily leaves are large, bright green and oval shaped with deep cleft that runs to near the center of the leaf.  The flowers are white with dozens of petals and numerous stamens. 

Fragrant Waterlily (Nymphaea odorata) in Salisbury, NC

Nuphar advena, the yellow pond lily or spatterdock, has floating leaves and a yellow flower that emerges above the surface of the water.  The petals of the flower are inconspicuous while the sepals give the flower its yellow color.  Spatterdock is widely used in traditional medicine to treat diarrhea and skin disorders. 

Spatterdock (Nuphar advena) in Palm Beach County, FL 

 Magnolias are a large group of highly successful basal angiosperms.  The family Magnoliaceae contains more than 200 species and they are found in North, Central and South America as well as East Asia. Two important members of this family in the Southeastern United States are Tulip Poplars and Southern Magnolias. 

Liriodendron tulipifera goes by a number of names Tulip Poplar, Tulip Tree or Yellow Poplar and is among the tallest eastern trees.   Tulip Poplars in the Joyce Kilmer Memorial Forest in western North Carolina tower to heights of more than 160 feet with circumferences of greater than 20 feet.  Tulip Poplars are fast growing, long lived trees that are valuable for timber.  Tulip poplar leaves are large with four lobes and its yellow-green flowers are tulip-shaped.  The flowers have 3 sepals, 6 petals with orange at their bases and multiple stamens and carpels. 

Tulip Poplar (Lirodendron
tulipfera) flowering in April, Salisbury, NC
The flowers are shaped like tulips.

Close up of Tulip Poplar flowers showing six petals, numerous stamens and carpels.

Southern Magnolia, Magnolia grandiflora, is a forest tree with large shiny green leaves and in late spring produces large, white, fragrant flowers.  One of the primitive characteristics of magnolias is their stamens and carpels are arranged in a spiral pattern rather than a whorl.  As the petals fall from the flower the spiral-pattern of stamen scars are apparent.   The carpels that produce the seeds are in a cone that also has a spiral pattern. 

Bud of Southern Magnolia (Magnolia
grandiflora) in Salisbury, NC

Flower of Southern Magnolia with multiple petals. 

Mature flower of Southern Magnolia.  It has multiple petals, many stamens
some of which have fallen on one of the petals and numerous carpels, 

Details of a Southern Magnolia flower.  Petals are inserted at the bottom of the flower.
Next come the yellow stamens and at the top are the many carpels that will produce seeds. 

A dying Southern Magnolia flower.  In the center is the carpel that will develop into
the seed bearing cone.  The purple column below the carpels has the spirally arranged
purple scars where the stamens were attached. 

An immature cone of Southern Magnolia
with its carpels and a few stamens
still attached.

Southern Magnolia cone.  Below the cone are
scars from the stamens and below them
are the spiral scars of the petals.

A nearly ripe cone of Southern Magnolia.  Seeds are developing
inside the cone.

A mature cone of Southern Magnolia.  The bright red seeds
are being released. 

By early fall, the cones split and show bright red seeds.  The seeds remain attached for a time attached to the cone by strong, silky threads that smell, oddly enough, like Juicy Fruit gum.  

Mature cone of Southern Magnolia with red seeds.

Southern Magnolia seeds are attached to the cone by threads
that smell like Juicy Fruit gum. 

These basal angiosperms are relics of deep time.  They remind us of a world long past.  So next time you see a magnolia or a water lily or a pawpaw, think dinosaurs.