Readers’ wildlife photos

This is the last full batch I have, though I’m saving singletons and the like for a melange post. But today is our first post (as I remember) that features carnivorous plants, from reader Jan Malik. Jan’s captions and IDs are indented, and you can enlarge the photos by clicking on them.

A few species of carnivorous plants grow in New York and New Jersey, primarily in swamps or bogs where it is difficult for plants to obtain nitrogen and phosphorus. Compounds of both elements are highly soluble in water and are poorly retained in waterlogged, low-pH soil. So far, I have found two species, each using a different strategy to catch its prey.

• Sundew (likely Drosera intermedia).
  “A small plant growing in the Pine Barrens of New Jersey. While there are other Drosera species in the Eastern USA, this one has leaves spaced along a short stem rather than a ground-hugging rosette. The plant must receive a rich payoff for the resources spent producing mucus and protease enzymes, as the remains of digested victims were obvious on many leaves. Research suggests that nitrogen from captured invertebrates can account for 30% to 70% of the plant’s total uptake, depending on prey density.”

• The “Expensive” Glisten.
  There must be something in the glistening droplets of mucilage on these tentacles that attracts insects. It looks like a lavish investment, but mucilage is mostly water with a small amount of polysaccharides to provide stickiness. The “expensive” enzymes are only produced after a victim is captured. I wonder if this secretion occurs only in the leaf where the victim is immobilized or systemically throughout the plant. In this shot, it even looks like the plant accidentally produced a web of sticky mucilage strands (on the right), mimicking a spiderweb.

• Digestion in Progress.
  An example of a fresh victim: a species of crane fly being digested. By plant standards, this process is quite fast; in a couple of days, little will remain except for fragments of chitin.

• Purple Pitcher Plant (Sarracenia purpurea).
  Photographed in the High Peaks region of the Adirondacks, NY, this species is a less “active” predator than the sundew. Both plants form traps from modified leaves, but pitcher plants form jugs that fill with rainwater. When small invertebrates (or occasionally small salamanders) fall in, they drown. Unlike the sundew, the pitcher plant generally doesn’t produce its own enzymes (except in very young pitchers); instead, it relies on a micro-ecosystem within the water—protozoa, mosquito larvae, and bacteria. These organisms decompose the victims, eventually releasing nitrogen and phosphorus for the plant to absorb through the leaf wall.

Carnivorous plants have a dilemma: how to capture invertebrates but let the pollinators live and do the job. The Purple pitcher plant soles it in the most logical way, by extending stems of its flowers so that they are far away from entrances to the pitchers. Apparently, that is the investment that pays off for the plant.

• Durability vs. Chemistry.
  Pitcher leaves are green in June but eventually turn deep purple. These plants are more cold-hardy than sundews and are likely the most northern-reaching carnivorous plants in North America. In the Adirondacks, they survive harsh winters buried under snow for half the year, and their leaves can remain active traps for several seasons. While Droserainvests in “biochemical weapons,” Sarraceniainvests in durable structures. Nutrient uptake is slower in pitchers but comes at a lower metabolic cost.

• The Downward Path.
  A close-up of the barbs on the lower lip of the pitcher trap. These guide victims downward, aided by scent and secreted nectar. Because they are downward-pointing, a victim has a difficult time climbing out, especially given the waxy, slippery surface of the leaf. Functionally, these barbs serve the same purpose as the sundew’s mucilage—preventing escape—but they are much “cheaper” energetically since they are part of the permanent leaf structure.