Denver EcoFlora Project's Journal

As Valentine's Day warms our hearts, let's explore the forest's most romantic residents—lichens! Imagine a love story where fungi and algae join forces, creating the ultimate power couple—that’s a lichen. Lichens are a symbiotic relationship between two or even three different species—one or two fungi paired with an algae or even cyanobacteria! These partnerships give lichens structure through the fungi and energy through the photosynthetic algae (you could say they’re a bit co-dependent).

In addition to being biologically fascinating, they are also ecologically important. They provide food, shelter, and even habitat for various other species. For example, birds will use lichens for building their nests—and tiny tardigrades (aka water bears) live within lichen like a real bear might live in a forest. Lichens perform ecosystem services like carbon capture, nutrient cycling, and can act as pioneer species, able to obtain nutrients from sheer rock and sunlight.

Beard lichens are a specific genus of lichens called Usnea. Although lichens are notoriously challenging to identify, this genus is quick to spot—look for tangled masses of silvery-green threads hanging from tree branches and bark. This genus is prolific in its range and grows from the Arctic to the tropics. Usnea is often confused with Spanish moss (which actually isn’t a moss or a lichen and doesn’t grow in Colorado). To identify Usnea, pull apart the outer sheath of its main stem. If there is tiny, white central cord inside, with the pull of an elastic thread—it’ll be Usnea. If not, it’ll likely be a different genus.

Usnea, and other lichens are known for their valuable benefits to humanity. For example, they are known for their usefulness in traditional medicine. The species in Usnea aren’t edible but are widely regarded for their medicinal uses, especially for their antibacterial and antifungal properties. Lichens are also known as bioindicators, meaning they can be used to monitor changes in environmental health. Some lichens, such as the beard lichen, are sensitive to common air pollution contaminants, like sulfur dioxide. This means that they can only thrive in areas with good air quality.

We still have a lot to learn about lichens. Learning more about where they grow can help us better understand air quality in the Front Range. In February, get more acquainted with this romantic fellow and contribute to our understanding of beard lichens by searching for these fascinating forest lovebirds and posting your findings on iNaturalist.

Usnea hirta by @phyllisholst

Usnea hirta by @bolmstead42

Townsendia, or Easter daisy, are one of the first plants to bloom in the foothills. Like their common name suggests, you will typically begin seeing them bloom around Easter. Although the weather can be quite cold this time of year, Easter daisy is adapted to withstand freezing conditions and blankets of snow. These plants form low mounds close to the ground, a successful strategy that helps to maximize heat retention during colder periods.

As a member of the Compositae (Asteraceae), or aster family, these “flowers” are not all that they appear at first glance. Indeed, what looks like a single flower is actually a composite of many flowers arranged in an inflorescence called a head. Inside of this head, there are even two different types of flowers present – ray flowers, which are petal-like, on the outer periphery of the head, and disk flowers in the center. These heads are nested amongst a rosette of leaves, protecting them from potentially cold conditions.

There are two species of Townsendia in the metro area that you might see flowering – T. exscapa and T. hookeri. These two species can be very difficult to tell apart – the main difference being that T. exscapa has larger heads with disk flowers over 6.5 mm while T. hookeri has smaller heads with disk flowers under 6 mm in length.

Documenting the flowering period of species such as these can ultimately aid our understanding of plant responses to a warming climate. By comparing observations, in combination with natural history collections dating back over 100 years, we can better understand how seasonal patterns are changing, and even make predictions for the future.

See if you can locate some Easter daisies and help Denver Botanic Gardens document their flowering period by photographing as many plants as possible in the month of March. Post your findings to iNaturalist so they will automatically be added to the Denver EcoFlora Project.

@astrobirder
T. hookeri

@christian_nunes
T. hookeri