Nature Ramble Report for June 9, 2022 
Leader for today’s Ramble: Dale
Authors of today’s report: Linda and Dale

Link to Don’s Facebook post for this Ramble All the photos that appear in this
report, unless otherwise credited, were taken by Don Hunter.  

20 Ramblers today.

Today’s emphasis:  The Yucca plants in the Dunson Native Flora Garden, wildflowers in the right-of-way, and further discoveries in the Dunson Native Flora Garden.

 

Reading:  Don read from “A Long Island Meadow,” a chapter in Frances Theodora Parsons’ According to Season, published in 1902.
    “The
brilliant coloring which is a feature of this midsummer meadow is
intensified by the insect life which it sustains. Butterflies,
especially, seem to abound. They float over the nodding grasses or poise
quivering above a nectar-laden blossom or rest on some leafy plant, the
dull undersides of their folded wings blending with their surroundings
and diminishing the likelihood of attacks from their enemies.
    Not
only is a butterfly endowed with unusual beauty, but its life-history
is full of charm. Then, too, the very names of butterflies breathe
romance (unlike those of birds and plants, of which “Wilson’s thrush”
and “Clayton’s fern” form fair samples). Who would not yield to the
spell of the Wanderer, the Brown Elfin, the Little Wood Satyr, and the
Dreamy Dusky-wing?  Or who could resist the charm of the Painted Lady,
the Silver-spotted Hesperid, the Tawny Emperor, or the Red Admiral?
    In
the meadow, perhaps, the monarch or milkweed butterfly is one of the
most omnipresent. Indeed, this is probably the best-known butterfly in
the United States, as its broad, orange-red, black-bordered wings carry
it many hundreds of miles and make it conspicuous everywhere. In
addition to being the most widely distributed, it is one of the most
interesting of our butterflies. Its career is an amazing one. How so
fragile a creature can endure the fatigue and resist the storm and
stress incidental to a journey of thousands of miles, such as it is
believed to take when migrating to southern lands, and how such a
“shining mark” escapes destruction from its enemies, it is difficult to
understand. That this annual migration does take place seems fairly well
established. The butterfly is known to have marvelous powers of flight,
and along the coast in fall it has frequently been seen assembling in
flocks numbering hundreds of thousands, changing the color of the trees
on which it alights for the night.”

 
Show-and-Tell: 

Gary brought some filamentous algae he collected from the water feature behind the Porcelain Arts Museum. Looks can be deceiving: the swaying masses of algae in the pool looked slimy but actually have a texture more like cotton candy.

Bill dissected a fresh Oak Apple Gall, exposing the larval Cynipid wasp in the fibrous mass suspended inside the gall. The gall formed when a female Cynipid wasp injected an egg into a vein of a developing leaf, hijacking the process of leaf development. Instead of producing a leaf, the plant responded to the invasion by forming a structure around the egg, both isolating and protecting it. The egg hatches into a larva then a pupa and ultimately into an adult wasp that chews its way out of the gall and takes flight. The gall doesn’t always succeed in protecting its larval resident however; birds such as woodpeckers and chickadees have learned to open galls to reach the snack that is captive inside.

Today’s Route:  We left the
Children’s Garden pergola and took the entrance road to the lower end of
the Dunson Native Flora Garden. We visited the Yucca patch, then the
adjacent right-of-way, and returned to the Children’s Garden by way of
the Dunson Garden and Shade Garden paths.

OBSERVATIONS ON TODAY’S RAMBLE

The paved walkway to the Children’s Garden is lined with Southern Magnolias, whose flowers are among the most dramatically beautiful in the world.

Adventures in the Yucca patch…

A storm-battered Yucca flower with central pistil (the ovary is green) and six stamens

At
the lower end of the Dunson Garden, near the sunny edge of the
right-of-way, there is a group of Yucca plants past peak bloom, the
nearly spent flowers suffering from a beating they took in last night’s
thunderstorm. Yucca flowers look like typical flowers, with a central
pistil composed of an ovary, a style, and a stigma, all of which
surrounded by a whorl of stamens producing pollen at their tips. But if
you look closely, the stigma – the sticky surface that receives pollen –
is not really apparent. In fact, it is tucked down inside a depression
at the top of the style. Why would a flower hide its all-important
stigma from potential pollinators? As it turns out, yuccas have a
special relationship with a group of pollinators – yucca moths – that
revolves around the hidden stigma.

Yucca moth

During the day, yucca moths
find shelter among the yucca flowers – shaking the stem of the flower
cluster flushes them out. The moths that fly out are small,
inconspicuous, silvery-gray insects that are so short-lived they do not
even eat. So, what makes them so special? When night falls, the
female moth flies from her shelter and begins gathering pollen from
the yucca flowers. She rolls the pollen into a ball, tucks the ball
under her chin, and flies to a flower on another plant. Using
tentacle-like mouth parts found only in yucca moths, she tamps the
pollen ball into the depression at the top of the style where the stigma
is located. When she finishes tucking the pollen into the stigma, she
walks to the bottom of the pistil and inserts a number of eggs into the
wall of the ovary – eggs that will develop into larvae (caterpillars) inside the ovary.
In a sense, she is farming yucca seeds to feed her young. The pollen she
tucked down into the stigma germinates, sending a pollen tube down the
style and into the ovary, where sperm are released and united with an ovule to begin the
process of seed formation. If the female moth has done her job properly,
there will be more than enough developing seeds to feed all her
caterpillars, with some left over to perpetuate the yucca.

But
what if she lays too many eggs? Or another moth chooses to lay eggs in
the same ovary? This is where the plant gets to “decide” what happens.
It can somehow sense when the load of caterpillars is too great for its
seeds to survive. Then the plant aborts the blossom, reserving its
resources for other flowers that will be able to produce an adequate number of
viable seeds. Researchers have examined aborted flowers and found
multiple ovipositing scars on their ovaries, showing that the moths
often lay more eggs that a single blossom can support.

When the
caterpillars mature, they eat their way out of the ovary and crawl into
the leaf litter on the ground below the plant and construct a cocoon.
Moths from some of these will emerge the following spring, but others
cocoons can remain dormant for several years. One entomologist had a
cocoon in a jar on his desk for over 10 years before a moth emerged.

Yucca Moth Caterpillar photo by Andy Reago and Chrissy McClarren, Flickr

This
is a matter of critical timing. The moths have a short life span and
they must emerge while the yuccas are flowering. If they emerge too
early, they may die before the yucca blooms; too late, and they will not
find any flowers to pollinate and oviposit in. How the plant and the
insect are synchronized is currently unknown.

There is one more
wrinkle in this system of checks and balances – cheating moths. There
are several species of yucca moths that lack the special tentacle of the
mutualist yucca moth. These moths can’t and don’t pollinate yucca
flowers, they just lay their eggs in them, taking advantage of the
efforts of other, pollinating, moth species. They are free-loaders,
parasites on a mutualistic relationship.

Eastern Leaf-footed Bugs are swarming all the Yucca plants.

Eastern Leaf-footed Bug adult and nymph

Rattlesnake Master (Eryngium yuccifolium) is not a yucca but the resemblance is reflected in the species name – yuccifolium – “yucca leaf.”

The flower heads of Rattlesnake Master are unique in the Carrot family. Shown here are immature heads that will expand into round, sputnik-like clusters.

Late spring wildflowers are abundant now in the right-of-way….

American Wisteria

Wild Petunia

Small’s Ragwort

Narrow-leaved Sundrops

Hairy Cat’s Ear, an invasive newcomer to our spring flora

In a case that seems a lot like natural justice, Eriophyid mites invade Poison Ivy leaves, creating galls that resemble the pustules that PI inflicts on its victims. Photo by Bill Sheehan.

Two bottomland tree species, Green Ash and Box
Elder, have opposite and compound leaves and produce winged seeds called
samaras. Their bark is similar too but their leaflets differ.

Green Ash leaflets have smooth margins.

Box Elder leaflets have toothed margins.

Maryland
Wild Senna, which blooms later in the summer, is found in drier and sunnier portions of the Garden’s
floodplain forest. We were initially confused about its identity in this immature stage but several features are diagnostic even now: large compound leaves
with smooth-margined leaflets, leaves with stipules at the base (at this
stage they resemble thorns), and one or two nectar glands on each leaf
stalk. Ants and small flies and bees gather nectar from the glands.
Maryland Wild Senna is a larval host plant for several species of
sulphur butterfly as well as silver spotted skippers.

Maryland Wild Senna

Maryland Wild Senna with narrow, pointed stipules at the base of the leaves and round nectar glands on the leaf stalks

This smooth, green caterpillar was seen on a Yellow Crownbeard stem. ID unknown, possibly Green Cloverworm (thanks, Avis!). Silvery Checkerspot caterpillars, which are known to use this species as a host plant, look very different.

From the floodplain, our return journey took us through Dunson Garden where a number of plants are in fruit or flower.

Goldenseal fruits resemble raspberries.

Fly Poison’s flowers start out white and turn green with age.

Black Cohosh flower spikes light up the understory like candles.

SUMMARY OF OBSERVATIONS:

Southern Magnolia     Magnolia grandiflora
American Nursey Spider     Pisaurina mira
Curly-leaf Yucca     Yucca filamentosa
Spanish Bayonet     Yucca aloifolia
Eastern Leaf-footed Bug (adult and nymph)    Leptoglossus phyllopus
Spotted Cucumber Beetle     Diabrotica undecimpunctata
Rattlesnake Master     Eryngium yuccifolium
American Wisteria     Wisteria frutescens
Small’s Ragwort     Packera anonyma
Hairy Cat’s Ear     Hypochaeris radicata
Narrow-leaved Sundrops     Oenothera fruticosa
Wild Petunia    Ruellia caroliniensis
Loblolly Pine     Pinus taeda
Poison Ivy       Toxicodendron radicans
Eriophyid mite     Aculops rhois
Trumpet Vine     Campsis radicans
Green Ash     Fraxinus pennsylvanica
Box Elder     Acer negundo
Maryland Senna     Senna marilandica
Green caterpillar    possibly Green Cloverworm, Hypena scabra
Yellow Crownbeard     Verbesina occidentalis
Basswood     Tilia americana
Fly Poison     Amianthium muscitoxicum
Goldenseal     Hydrastis canadensis
Black Cohosh     Actaea racemosa
Green Lacewing (larva)     Chrysoperla rufilabris