Wednesday, June 24, 2015

Indian Pipes: Ghost Plants

Indian Pipes, Ghost Plants, in bloom.

     Few plants are as eerie or strange as Monotropa uniflora, a native plant with numerous names describing its unusual features. The scientific name translates as "once turning single flower." But they're probably best known as Indian Pipes due to the shape of the flowers, which look like the Native American Indian calumet, or "peace pipe." More names and their sources will become apparent as I describe the plant in more detail.
     These perennial plants are members of the Ericaceae or Heath family, but many people think them to be fungi when they first encounter them. They have a waxy appearance (sometimes the are called Wax Plants), very few scaly leaves, and are white or pale due to their lack of chlorophyll. They have no need for chlorophyll because they do not produce their own food through photosynthesis, being some of the 3,000 or so plants that lack this trait.
     But Ghost Plants, as they are sometimes called due to their eerie appearance and tendency to grow in the deep shade, are in an even more unusual group of flora, considered epiparasites and referred to as mycoheterotrophs. 
     These types of plants were once believed to be parasites feeding off the roots of certain trees, but life for them is much more complicated. They actually depend on certain mycorrhizal associations. Many people are not aware that a great many of our native plants have a positive symbiotic relationship with certain mycorrhizal fungi, some cannot even exist without them. These fungi provide certain services and nutrients to plants in exchange for others, a mutually beneficial arrangement for both.
     Mycoheterotrophs like Monotropa insert themselves into this arrangement. They steal some of the nutrients the plant was sharing with the fungi. They are mycorrhizal cheaters who steal what they need to survive in a strange menage a trois. They cannot survive without either the plant (certain tree species such as beech) and mycrrhizal fungi, mostly in the Russula and Lactarius genus. They intermingle their roots with the fungi in a tangled mess giving the plants the alternate name of Bird Nests.
   Though this solves the problem of obtaining nutrients, it does not solve the problem of pollination. So once a year they need to send flowers up above the soil surface for pollinators to visit (mostly bumblebees). That is when we notice the Ghost Flowers or Fairy Smoke as they are sometimes called. 
     The blooms straighten and point upwards once they are pollinated, ready to produce seeds. The seeds however need to land somewhere where the specific mycorrhizal fungi and trees are bound together or they will not survive. This makes these plants extremely difficult to propagate and almost impossible to transplant as you break the necessary connections should you attempt to do so.

Corpse Plants straightening out after pollination.

     The flowers do not last very long if they are picked or even bruised. They appear to decompose rapidly upon being disturbed, melting away and darkening in a gelatinous mess that gives them the alternate names of Ice Plants, Corpse Plants, or Death Plants.
     These plants have been used in various fashions by people. The Cherokee sometimes used the pulverized roots to treat convulsions, epilepsy, and fits. Colonists later on used them in similar fashion resulting in their being called Fit Plants or Convulsion Weeds. Colonists also learned to use the plant juice for eye problems as the Cherokee did, giving them the other name of Eyebright. The crushed plant also was applied to warts and bunions.
     Other tribes such as the Mohegan believed that this plant could treat colds and fevers. The Cree chewed it for toothaches, the Thompson would treat sores and saw it as a sign that where they were found would be good for foraging mushrooms. Indian Pipes contain glycosides and are considered toxic these days.  
     These are indeed strange but wonderful plants. Their haunting appearance in dark woods may seem eerie, but just goes to show you the complexity of the natural world.

Tuesday, June 23, 2015

Bunny Boom

Eastern Cottontail Rabbit

     People may have noticed quite an increase in the number of rabbits they are seeing in certain places this year. This is due to a couple of factors. First of all, many of our native Eastern Cottontail (Sylvilagnus floridanus) rabbits have just completed weaning and are heading off on their own to find new places to live. Many of these rookie rabbits do not make it very far, ending up hit by cars, picking poor locations to live, or eaten by predators, but many at least temporarily do.
     I also suspect that there may be more rabbits about because of a decline in one of their main predators. Red foxes suffered from an outbreak of sarcoptic mange over the last year. This caused numerous fatalities and thus less predatory pressure on cottontails, allowing their numbers to expand. Rabbits can make up to 50% of the diet of foxes and they are their most important predator. For more on the red fox, who weren't originally part of our landscape, check out this previous Blog entry on them:   

     The Eastern Cottontail is quite common throughout our region, and indeed throughout the East. Having 3-4 (up to 7) litters a year of 3-6 bunnies each (after about a month's gestation), they can reproduce quite quickly. But since they're a favorite meal for many hawks, owls, foxes, cats, bobcats, dogs, large snakes, coyotes, possums, mink, skunks, weasels, and even crows, mortality rate is close to 80% of the adults a year. Even fewer rabbits even make it to adulthood. Fifteen months is a good average old age in the wild, while in captivity they can live to 5 years. Injured rabbits give quite an eerie scream. This often attracts predators, a trick learned by hunters using artificial game calls to lure them in.
     Young are born in a depression usually hidden in the brush or grass. This is sometimes called a "form" and is lined with leaves and fur. Baby rabbits are born naked and with eyes closed (unlike Hares which are born haired and with their eyes open, and who also have longer ears). Two to four weeks later, they're hopping off on their own, often themselves ready to mate at 2-3 months of age. Males rabbits are called "bucks" while females are called "does."
     Rabbits (along with hares and pikas) are called "lagomorphs," differing from rodents by having long back legs, often large ears, short tails, and most especially an unusual tooth arrangement. Lagomorphs have a double set of upper incisors, one set right in front of the other. Cottontails are herbivores and are coprophagous (eating their own green fecal pellets the first time it goes through their system to get the most of what they've eaten).

Two rabbit skulls, with the double incisors visible on the left one.

     Many people think that all rabbits live in holes (called "warrens" in Europe where their rabbits do live in burrows), but our native cottontails do not do so. They may "hole up" in a groundhog hole if being chased or in extreme weather, but they actually live above ground. Most maintain a home range that's about 100 yards or so, though this varies, with males especially having larger ranges. They do not like to venture out of this small territory, running in zig zags, flashing their tails, but usually circling around at some point rather than leave their familiar territory.
     Cottontails have actually increased their distribution, living now in New England and some parts of Canada where they did not do so before. They've also been introduced to several islands and have bred, well, like rabbits, now being numerous in those places.
   So enjoy the cottontails while they're around. Though they may eat some of our garden plants, they will not be around for long. Something will end their lives shortly, be it cars, diseases like tularemia, or predators. Bunny booms are short lived.

Saturday, June 20, 2015

Beetle Pollinators

Long-horned Locust Borer Beetle (a yellowjacket mimic) on Goldenrod

     To continue with National Pollinator Week, let's look at one of the least known, but vital, pollinators: beetles. Due to their sheer numbers (there are more beetle species than any other group of animals studied), they are responsible for a considerable amount of plant pollination. They are also one of the most primitive pollinators, among the first group of animals to start visiting flowers. Beetles are still the primary movers of pollen for numerous plant families, especially primitive ones like magnolias.

Chafer Beetles on Maple-leaf Viburnum

     Although many beetles can see color, they often depend on detecting the aromas of the blooms instead. These are not always pleasant smells (or the brightest colors) either, since they are attracted to numerous kinds of odors, including those of rotting meat for instance. That's why many beetle pollinated plants are brown or dark and not the most pleasant to us. 
     Beetles also pollinate in a different manner than most other pollinators. Many of them actually eat the pollen, and in so doing, transfer it to other flowers. They often defecate in the flowers while eating there and so are sometimes referred to as "mess and soil" pollinators.

Margined Leatherwing Soldier Beetles mating while pollinating Dogbane

     Beetles also often have more reasons that just a meal to visit flowers. Since they are grouping there already and are attracted to the flower due to smell and/or color, they make a great place to meet other beetles. Beetles often use the blooms as places to mate, sometimes having orgies in the flowers themselves. 

Click Beetles inside a Sessile Trillium flower

     So beetles may not be the most obvious pollinators, or even the prettiest or best, but they are vital for the pollination of many of our plants. They may even have ulterior motives for visiting flowers, to eat the pollen or sex, but they are important, if under appreciated none the less.

Tuesday, June 16, 2015


Metallic Sweat Bees feeding on a Greenheaded Coneflower

     In honor of National Pollinator Week, it makes sense to honor the best of all the animal pollinators: bees. Most people are aware of how important bees are for pollination of plants, including some 70% of our crops. What they do not often realize however is that we have some 400 or so native bee species in our region, most of which are not at all like the introduced European Honeybee. Honeybees were were brought to the USA in to Jamestown, Virginia, in 1627. They are of course extremely valuable for the way we conduct our agriculture and to give us honey, but we need to realize that wild plants were doing fine (maybe even better) before these generalist bees arrived. Our native plants likely would do fine whether honeybees were here or not today. While most people think that all bees are like the social European honeybees (living in hives with a queen, making honey, and only capable of stinging once), they really are the exception and different from the other 4,000 or so other species we have in North America. There are also about 40 species of non native bees in the US, including the European Honeybee.
     The vast majority of our native bees, for example, are actually solitary, with a single female bee taking care of her young, collecting nectar and pollen for them all by herself. She is extremely non-aggressive and many are incapable of even having their stingers pierce our skin. Should that unlikely event happen however, multiple defensive stings are possible. The reason solitary bees do not sting is that they would prefer to fly away and not defend their nest, for if the solitary mother dies, her nest and eggs are dead anyways. Better to fly away and start over. Honeybees on the other hand live for the hive, the workers themselves really not even reproducing, so all they care about is defending their nest, even if they lose their lives stinging in the process.
     Male solitary bees also fend for themselves and are efficient pollinators by the way, unlike male (drone) honeybees. They have no one to feed them other than themselves and so visit flowers and pollinate plants much like the females. No male bees of any species (or wasps for that matter) can sting either, since stingers are modified ovipositors (egg layers) and males cannot lay eggs of course. Only female bees sting.

Ground nesting bees and their holes

     70% of all bees live underground, while the other 30% often rely on cavities in trees, plants, walls, and many other locations. They usually use burrows they dig and then provision with nectar and pollen for their developing young. While each solitary bee lives by herself and takes on all the work alone, if the habitat is right, many female bees may nest near each other. Good real estate in a nice neighborhood can be hard to find (especially since agricultural practices like plowing can be so detrimental to them). After collecting enough food and laying eggs, the mother bee dies and the bee larvae develop on their own until they emerge, often the next year. 
     Another thing many people do not realize is that although bees can visit many different types of flowers to feed on for themselves, almost half of our native species are specialists in the type of pollen they need to feed their young. These specialist bees, often needing the pollen of a single family, genus, or even a single species of flower, are called oligolectic bees. If the specific (normally native) flowers are not available, the bees cannot reproduce. This is another reason to include a great diversity of native flowers in our yards and preserve them in our parks. Bees need the flowers they evolved with or they simply cannot survive.

Hibiscus Bee Ptilothrix bombiformis, digging her burrow

     The one shown above is usually called the Hibiscus Bee, Ptilothrix bombiformis, which needs pollen from plants in the Mallow family (including hibiscus) to reproduce. I noticed these digging their burrows in one of our Natural Resource Conservation Areas, Arlington Forest Park. They do indeed look like a bumble bee (thus the scientific epithet bombiformis meaning "in the form of a bumblebee"), but unlike them, they dig solitary burrows in the ground. Thanks to friend and colleague Sam Droege, one of the best bee guys in the country, for the help in identification.
     These bees are remarkable in that they not only dig burrows, but carry water over on their fuzzy bodies to wet the ground enough to help them in their excavation. The dirt they pull out is often formed into little turrets that surround the entrance to their hole. They are living in this park because they have the bare, well-drained ground they need, a water source nearby, and of course the plants in the Mallow family that they require.
     This is just one of our 400+ bee species. So this National Pollinator Week, honor all pollinators, but realize that none are better than our native bees.

A male Perplexing Bumblebee (Bombus perplexus) pollinating a flower. Bumblebees are one of the few native social bees, though their nests only last one season.

Monday, June 8, 2015

Milkweed Traps

A skipper butterfly sips nectar while its moth cousin has gotten stuck and cannot get loose.

Another moth that was too weak to remove the pollen sacs and died.

While a hairstreak butterfly feeds, an unlucky moth dangles dead when it could not free itself.

     Something many people are not aware of what goes on unseen on the milkweeds in bloom right about now. Most people are aware of how attractive these flowers are to insects. Not only are they covered in many pollinators during the day, but are very active at night as well, especially with moths and beetles. Some milkweeds, like Common Milkweed (Asclepias syriaca), are specially fragrant and attract numerous insects both day and night with their rich nectar supply. But many of these pollinators who are attracted are not designed to remove the pollinia (pollen sacs) that milkweed have and are not the proper pollinators.
     Pollinia (singular pollinium) are pollen grains that are grouped and stuck together, designed to be moved as a unit, like a single structure. They almost look like small saddlebags in milkweeds. It takes large specialized pollinators to move them properly. Those that are too weak are sometimes trapped and may lose legs trying to escape, or even die. Here are a few photos from a single milkweed patch on one day showing a collection of small moths who were unable to get away and died. Most have stuck legs, but a few had their proboscis stuck as well. Others are scavenged by the many insects that patrol the flowers and so they are not around for long. That means that this is but a small number of the insects who got themselves trapped. It can be dangerous being a pollinator.
     Here's a European Honeybee who likewise got itself trapped. Note the pollinia stuck to its legs.

A European Honeybee trapped on a Swamp Milkweed. Note the pollinia stuck to its legs. 

     Here is a short video from the Capital Naturalist YouTube Channel that shows the struggle a honeybee goes through after getting trapped by the pollinia:
      It's amazing the drama that goes on on a miniature scale in nature, even on something as beautiful and harmless looking as a flower...