A Plant with Teeth

My neck of the woods isn’t like the Chihuahuan Desert, where nearly everything that photosynthesizes seems like it evolved to grab, shred, tear, puncture, and stab you (just try an off trail hike at Carlsbad Caverns National Park if you want the experience and say hello to the lechuguilla while you do). Nor is my habitat like the poison-oak dominated slopes found in coastal California where a careless walk through brush can leave you itchy for weeks. No, not like that. Heck, I don’t even need to worry about ticks.

Along the Skagit River, devil’s club and a couple of species of invasive blackberry will stop you in your tracks with their numerous, stout thorns. Besides those few, the list of plants to avoid drops off fairly quickly, with a notable exception. One of the most ecologically interesting and menacing members of my plant community is a nondescript perennial that’s easy to ignore until it’s too late.

Lots of plants are fuzzy with fine hair. Some plants, like common mullein (Verbascum thapsus), utilize hairs on their leaves and stem like sunscreen and to make grazing just a little uncomfortable for herbivores. Some hair is just there, perhaps not serving a specific adaptive purpose, or not one that we know currently. But one plant in my forest, Urtica dioica or stinging nettle, has turned their hairs up to 11.

Nettle is rather inconspicuous. It has oppositely-arranged, coarsely-toothed, and heart shaped leaves. Its flowers grow in small, string-like clusters from the leaf axils and lack petals, typical for a wind pollinated plant, but what it lacks in showiness it makes up in its ability to inflict pain.

group of densely growing plants with toothed, heart-shaped leaves

Stinging Nettle (Urtica dioica)

I learned about stinging nettle as a young teenager scrambling up a creek bank in Pennsylvania. The bank was steep and muddy. I needed just a little extra support to prevent me from sliding down. Lacking a tree to hold, I grabbed a group of herbaceous stems and immediately realized I had made a mistake. I made it up the bank, but the palms of my hands burned for the rest of the day. I was just introduced to nettle’s defense against mammalian herbivores.

Stinging nettle is equipped with tiny, but potent, stinging hairs. On the plants in my area, the hairs are particularly concentrated on the stems, flowers, petioles, and leaf undersides. Each hair is tipped with a small, fragile bulb that breaks off when contacted to expose a needle-like tip that, hardened by calcium carbonate and silica, readily injects a cocktail of chemicals into your skin. The stinging sensation is immediate and long lasting.

close-up view of underside of stinging nettle leaf showing stinging hairs, petiole, and leaf veinsclose-up view of young stinging nettle stem with many stinging hairs

Among other chemicals, the juice inside a hair contains histamine, which is an inflammatory compound (we take antihistamines to inhibit the affects of allergic reactions), and serotonin, which constricts blood vessels and acts as a neurotransmitter. In sum, it is designed to irritate.

Why the need for this defense? Nettle leaves are nutritious and high in vitamins A and C as well as protein. They would likely be a sought after commodity by deer and other browsing mammals if it weren’t for their stinging hairs.

We can neutralize the sting by drying or steaming the leaves. Steamed, the leaves taste as mild as spinach and they make a decent pesto.

 

The rash you get from poison ivy is an accident of evolution. The oily liquid, urushiol, which causes the itchy dermatitis on us doesn’t affect other North American mammals or birds. Your dog won’t get it. Deer eat the leaves. Many bird species relish poison ivy fruits for food. The stinging hairs on nettles tell a different story. They are purposefully indiscriminate against all mammals.

Plants, like all life forms, experience a wide variety of limiting factors. Stinging nettle may have evolved one way to dissuade herbivorous mammals, but the same defense doesn’t deter insects or snails. The stinging hairs don’t work on parasitic fungus or microorganisms either, nor on anything that attacks and eats its perennial rhizome. But, its stinging hairs work, quite well in fact for their evolved purpose—discouraging mammals from eating it.

Despite the pain nettle can inflict, I look forward to seeing it sprout each spring. It gives me an opportunity to reflect upon why it needs to evoke such discomfort in mammals. Stinging nettle is a plant with teeth. It fights back.

Someone’s eating the berries

In low elevation areas at the foot of the North Cascades, salmonberries are quickly ripening and I have plenty of competition in the race to harvest them.

ripe salmonberrySalmonberries (Rubus spectabilis) are moderately tall shrubs with compound leaves and bright magenta flowers. The flowers later produce large, raspberry-like fruit in various shades of yellow, orange, or scarlet. According to Cascade-Olympic Natural History, the plant’s common name derives from the fruit’s ability to cut the greasiness or fishiness of salmon, not from their color. Like many sugary, wild fruits, they are relished by more than humans. Recently, other critters have beaten me to the choicest berries.

stem of plant missing its fruit

Increasingly often, I find salmonberry shrubs stripped of their ripe berries.

 

Bears, of course, will eat salmonberries, but most of the berries I’ve seen have been plucked a bit too delicately to be the work of a bear. Bright red or yellow berries aren’t just an advertisement for mammals. They attract birds as well. Cedar waxwings, in particular, are pronounced frugivores and I recently watched a few in the act of stripping a salmonberry shrub clean.

I’ll gladly yield the fruit to these birds, since they’re doing the legwork (or is it wing-work?) to disperse the seeds. In the waxwing’s digestive tract, the seeds are carried far and wide, and if the seed is extremely lucky the bird will deposit it in a moist, sunny spot with rich soil.

More than waxwings influence this plant’s reproduction, however. Earlier this spring, I watched many rufous hummingbirds visit its large magenta flowers.

magenta colored flower with five petals

The salmonberry flower.

Salmonberry blooms relatively early in the spring (I found it in full bloom in mid April this year), a time when few other hummingbird flowers are present. Salmonberry plants aren’t exclusively pollinated by hummingbirds, but I watched hummingbirds frequently visit more than one patch of salmonberry blossoms this spring, so it may be an important early source of nectar for them.

In blossom and in fruit, salmonberry is tied to birds. Have you noticed similar connections in your local ecosystem?

Flower, You Stink

Throughout much of temperate North America, late spring and early summer is a wonderful time to enjoy wildflowers. I like looking at plants for many reasons, but recently I’ve begun to think more carefully about their smell. I’ve been sniffing plenty of flowers lately, and not all are pleasant.

Most flowers that we notice need a pollinator, but pollinators aren’t volunteering their services. They seek a reward for the effort to help the plant complete its reproductive cycle. Most of the time, the reward comes in the form of pollen or nectar or both (although there are some amazing examples of plants deceiving their pollinators). Other than visual cues, scent is one noticeable way flowers advertise their wares. Ever smell a wild rose, for example? They are sweetly fragrant, even from a few meters away, and are popular with bees and butterflies, who seek out their pollen and nectar and pollinate the plant in the process.

two rose flowers with pink petals

Rosa nutkana, the Nootka rose.

I’ve sampled the perfumes of many plants recently, giving me a tangible way to understand their different reproductive strategies. The scent of flowers, not surprisingly, ranges from non-existent to downright stinky.

Lupine, another plant popular with butterflies and bumblebees, is very odorous, smelling sweetly florid and very noticeable while walking through a meadow. The same goes for snowbrush ceanothus (Ceanothus velutinus), whose flowers attract a wide variety of insects.

cluster of white ceanothus flowers at the end of a twig

Ceanothus velutinus, commonly called snowbrush ceanothus.

Hawthorns (Crataegus sp.) and black cherry (Prunus serotina) are faintly malodorous, at least to my nose. Consequently, they attract a different suite of pollinators than roses even though they are in the same family (Rosaceae). Bees visit these plants but so do lots of flies.

flowers, Prunus serotina, Moraine State Park_05182017To increase the skink level another notch, take a whiff of mountain-ash (Sorbus sp.) or yarrow (Achillea millifolium). Mountain-ash and yarrow are in different plant families, Roseaceae and Asteraceae respectively, but they share one trait: their flowers smell like shit.

flowers, Sorbus scopulina

The first time I discovered the scent of mountain-ash, I thought I had stepped on a dog turd.

fly on cluster of white flowers

Yarrow is surprisingly stinky, which would explain why flies that you’d find on scat also visit this plant’s flowers.

Why smell like animal scat? Not all insects seek the same odors. Many species of flies, as we know, are attracted to carrion or scat. Flowers that mimic these odors are often seeking pollination from flies. From the plant’s perspective, it doesn’t matter what insect provides the pollination as long as the work of pollination gets done.

There’s sweet, there’s stinky, and then there’s unscented. I couldn’t detect the any scent from wild ginger (Asarum caudatum) flowers, but the plant was very odorous and smelled, well, like ginger. Its flowers hide on the ground, but this plant may be self-pollinated more often than not.

maroon colored flower among fallen leaves

Asarum caudatum, wild ginger, flowers hide on the forest floor.

Orange honeysuckle (Lonicera ciliosa), from my limited observations, is pollinated exclusively by hummingbirds. The bright red-orange flowers are striking and easy to see, but have no scent, at least none that I could discern. Hummingbirds have little to no sense of smell. If your flowers, like the wild ginger’s, are mostly self pollinated or your pollinators can’t smell you, then there’s no need to expend energy producing scent.

When we walk into or even near a floral shop, the air smells strongly of perfume, an odor most of us would describe as florid. In nature though, the perfume of flowers is extremely varied. They smell fruity, sugary, stinky, rotten, inodorous, and everything in between. Flowers, in my opinion, are nature’s most conspicuous display of sex and scent is a technique plants use to get what they need—pollination—to reproduce.

 

First Flowers

Spring has officially arrived in the northern hemisphere, and southwestern facing slopes in the North Cascades, especially near Lake Chelan, are thawing quickly. This is where I seek the first herbaceous and mossy greenery of the year.

leaves and moss on rock

Green leaves and vibrant moss are a welcome sight after a snowy winter.

At the lakeshore, approximately 1100 feet (335 meters) in elevation, deep snow and relatively mild winter temperatures (daily lows for December through February average around 25˚F/-4˚C) prevent soil from freezing significantly. During late winter and early spring, sunlight directly strikes the southwestern facing slopes along the lake. Bare rock and tree trunk create heat islands that further warm the soil and melt remaining snow. The first wildflowers of the season bloom here, taking advantage of conditions that higher elevations will not experience for months. Two species are just setting blossoms now.

wildflower with umbel of yellow flowers and pinnate leaves, among other small vegetation

Wyeth biscuitroot (Lomatium ambiguum) near Stehekin Landing.

wildflower with umbel of white blossoms and pinnate leaves

Geyer’s biscuitroot (Lomatium geyeri) near Stehekin Landing.

Biscuitroot (Lomatium sp.), also called desert-parsley, is a large and widespread genus of plants in western North America. The species I found are not exclusively restricted to the rocky areas near the lake, but these individual plants have found an ideal early season microhabitat. The slopes where these plants grow are very warm, although it may not seem that way when they are dripping with snowmelt.

bright green moss, dripping with water, on side of rock

Anyplace it is exposed near upper Lake Chelan, moss is saturated with snow melt.

By the end of June, perhaps even before, these plants will be parched by low humidity and scorched by high daytime temperatures. The soil, instead of wet and clumpy, will become dust. Flowering plants in this location do their business quickly—blooming and setting seed before the soil completely desiccates and ground temperatures become too hot. They get ahead now, because conditions allow them to. Up valley and higher on the mountainsides, under the snow, other members of their respective species are waiting for their own moments in the sun. It’s only a matter of time.