Category Archives: natural history

The Trees of the Northwest

The trees of the Northwest are old and large and as a rule, rarely lose their leaves.

They are Ever Green in the Evergreen State.

Except when they’re not.

The Douglas Firs, the Western Red Cedars, the giants whose girth took a dozen loggers to fell —

These are the iconic trees of the Pacific Northwest.

Except when they’re not.

Except when the tree, as common as pancakes, is a maple.

Its stature and shape won’t catch your eye like the thousand-year giants with the bark that puts off rotting for another rainy day.

But the maple’s blocky gray skin still reads like Braille beneath a girl’s fingertips, telling her to look up.

To see the spaces where the new leaves — Bigleaf but not yet big — overlap up to the canopy,

where the wind shuffles their new cells,

still supple with growth.

Looking up into the branches of a Bigleaf maple tree

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Wet Winter Reflection

Cedar branches hanging over ferns.Mossy tree branches over a trail.

Even in winter,

Seattle’s five o’clock shadow is moss,

Its ferns hold fast to the hillsides,

And its evergreens keep their eponymous promises.

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Plants vs. the World

A stinging nettle.

The world is a rough place to grow up. Just ask a stinging nettle. Credit: Ashley Braun/All rights reserved.

Life as a plant can be stressful. Once, or rather, if, you sprout where you’re planted, you’re faced with some immediate limitations. Let’s hope you have just the right exposure to sunlight, water, and nutrients. Maybe not too much wind or competition for space. And watch out for herbivores.

But that’s about all plants can do, right? Just watch.

While plants do have some obvious defenses (thorns, toxins, tannins, and the like), we humans often think of plants as being passive. We don’t give them much credit for taking a stand against the world. “Vegging out” means sitting around doing nothing, unaware and unresponsive. Yet researchers are finding many examples of plants actively responding to the world around them and in a variety of ways.

Yo, Romeo: Smell Ya Later

Tall goldenrod plant with fly-induced gall.

I forgot to mention that gall fly larvae spit causes huge galls (ball-shaped masses) to form on the goldenrod’s stem. They then live inside the gall all winter, sucking nutrients out of the plant from the inside. No wonder the plant is pissed. Credit: Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor/Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.

Take smelling, for example. In 2012, entomologists at The Pennsylvania State University documented both in the field and in the lab evidence of a plant that, when exposed to the smelly male sex hormones of a long-time enemy, is able to beef up its chemical defenses against it.

It seems that once the tall goldenrod plant, Solidago altissima, gets a whiff of a romantically inclined male goldenrod gall fly, Eurosta solidagini, it begins releasing the defense hormone, jasmonic acid, which is a real turn-off to lady flies. Particularly, as it turns out, when they’re looking for a place to lay their eggs, which hatch into hungry little caterpillars and only have a stomach for tall goldenrod.

Male flies release clouds of this pheromone “perfume” when they’re in the mood for love, sitting on the leaves of a tall goldenrod plant and waiting to attract a female. After they mate, the female flits away to find a suitable nursery plant for her bug babies. In this search, she goes from plant to plant, sticking her egg-laying organs into goldenrod buds and getting a “taste” for the plant with her feet and ovipositor. If she likes the taste, she lays her eggs. If not, on to the next plant.

However, once a plant is exposed to the male flies’ odor, not only are they less likely to have female flies inject their eggs into them, but to a large extent they also avoid being eaten by other hungry insects. Jasmonic acid must taste terrible to a would-be mother goldenrod gall fly. But the musk of a male fly apparently smells like heaven to a nervous goldenrod.

Beating the Heat

Another very real concern for plants is heat stress, which is only going to get worse as the global climate warms. The United Nations Intergovernmental Panel on Climate Change is in the process of releasing its latest series of reports on global warming and its impacts on the natural and human worlds. A part of one of their reports was leaked before being published, but it apparently has dire warnings for agriculture.

According to the New York Times:

In a departure from an earlier assessment, the scientists concluded that rising temperatures will have some beneficial effects on crops in some places, but that globally they will make it harder for crops to thrive—perhaps reducing production over all by as much as 2 percent each decade for the rest of this century, compared with what it would be without climate change.

And, the scientists say, they are already seeing the harmful effects in some regions.

Heat waves have already taken a toll on crop production in recent years (see Europe in 2003). A growing body of research suggests that important crops such as corn and soybeans are more sensitive to extreme heat than previously thought.

What does “extreme heat” mean? The mid-80s. Having grown up with sticky Midwestern summers, that doesn’t even sound that hot, but it translates to a sudden drop in production for these plants.

Even so, plants do have ways to cope with heat stress. Researchers at Iowa State University have recently uncovered some of the molecular pathways that plants use to deal with stress. From a press release:

The research takes a close look at what happens to the model plant Arabidopsis at a molecular level when faced with environmental stress. It involves a process called unfolded protein response, which can act as an alarm system when the plant senses harsh conditions. When the alarm goes off, the plant activates survival measures that can protect crops from succumbing to weather extremes.

Considering the warming world facing plants, they’re going to need these kind of defenses to stay alive. And why should we expect them to just sit back and watch?

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I Flew Over the Cuckoo’s Nest

Baby got snack: A Reed Warbler feeds a Common Cuckoo in its nest.

Baby got snack: A Reed Warbler feeds a Common Cuckoo in its nest. Credit: Per Harald Olsen/Creative Commons Attribution-Share Alike 3.0 Unported license

Earlier this week, I was researching and writing a story for Natural History Magazine about some cuckoos that have taken on the plumage patterns of local hawks and other raptors in order to frighten away other birds from their nests.

“Dressing” like a known predator allows the cuckoos to swoop in and lay their own eggs in the nests, tricking unsuspecting sets of bird-parents into raising the cuckoos’ young. This sometimes happens to comedic effect when you consider how much bigger cuckoos can grow than their host parents.

(By the way, you should read the bio of Thanh-Lan Gluckman, one of the scientists who published the study on cuckoo-raptor plumage; she has taken a fascinating, if self-described “convoluted,” path to evolutionary biology.)

In the course of researching this story, I followed an interesting tangent: In 350 B.C., the ancient Greek philosopher Aristotle made observations in his work “The History of Animals” about both the behavior of cuckoo parents and their striking resemblance to hawks. Stringent scientific studies today support these observations as well as the maxim shared with me by my college ecology professor: Basically, ecology confirms what we already know.

One thing I found amusing about reading these early descriptions was the moral lens through which the cuckoo is viewed for its habits (emphasis is mine):

The cuckoo, as has been said elsewhere, makes no nest, but deposits its eggs in an alien nest, generally in the nest of the ring-dove, or on the ground in the nest of the hypolais or lark, or on a tree in the nest of the green linnet. It lays only one egg and does not hatch it itself, but the mother-bird in whose nest it has deposited it hatches and rears it; and, as they say, this mother bird, when the young cuckoo has grown big, thrusts her own brood out of the nest and lets them perish; others say that this mother-bird kills her own brood and gives them to the alien to devour, despising her own young owing to the beauty of the cuckoo … The cuckoo shows great sagacity in the disposal of its progeny; the fact is, the mother cuckoo is quite conscious of her own cowardice and of the fact that she could never help her young one in an emergency, and so, for the security of the young one, she makes of him a supposititious child in an alien nest. The truth is, this bird is pre-eminent among birds in the way of cowardice; it allows itself to be pecked at by little birds, and flies away from their attacks.

~Aristotle, “History of Animals,” Book IX, Part 29, 350 B.C.

Yes, the cuckoo is full of “cowardice” and is quite aware of it, thank you. On the other hand, the foster-parent bird purportedly “despis[es] her own young owing to the beauty of the cuckoo.” Naturally, they’re going cuckoo for cuckoo chicks!

This tangent took me further down the rabbit hole to the 1891 work of Alfred Russel Wallace, “Darwinism: an exposition of the theory of natural selection.” Wallace makes further reference to how similar several species of cuckoos appear to sparrow-hawks and other “aggressive” birds, despite–or rather because of–the cuckoos’ “exceedingly weak and defenceless” nature.

Darwinism: an exposition of the theory of natural selection, with some of its applications

“Darwinism: an exposition of the theory of natural selection, with some of its applications,” by Alfred Russel Wallace, 1891.

It’s worth noting that not all cuckoos (the family Cuculidae) exhibit these parasitic adaptations to reproduction. But approximately 41% of them do.

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