Nature News: Pixie cups and powderhorns in Santa’s garden
When my kids were little, one of our favorite wintertime activities was getting outside to look for some magic in nature. One of our favorite discoveries that we decided had something to do with Christmas were the tiny pixie cups (obviously used by Santa’s diminutive elves), red-topped British soldiers (we likened these to the more seasonal nutcrackers) and powderhorns (unfortunately, we never figured out how to connect these to Santa) sprouting from the rotting stumps in our neighborhood wetlands.
Higher up on the slopes of our local Agamenticus and Bauneg Beg Mountains were another worthy addition to the holiday: microflora-reindeer lichen.
While we obviously invented these seasonal connections with European Christmas traditions, we didn’t invent the magical creatures themselves — tiny lichens inhabiting a Lilliputian forest of mosses, ferns and mushrooms. As I have learned about lichens I have come to understand they truly are everywhere and play a fascinating role in local ecosystems. Lichens are estimated to cover 7% of the Earth’s surface. Compare this to tropical rainforests which cover an estimated 6% of the Earth’s surface (National Park Service) or the 9% covered by deciduous trees (temperate forest like where we live). Seven percent is a lot!
Lichens are fascinating organisms composed of a symbiotic relationship between fungi and algae or cyanobacteria (or sometimes both as well as a potential slew of other organisms) in which the fungus provides a structure that houses the algae while the algae (or cyanobacteria-a photosynthetic bacteria) provides food for the fungus by performing photosynthesis. They don’t have a vascular system like most plants so can’t transport water and nutrients throughout their bodies and so can’t get very big. Instead they consume the sugars produced by their photosymbionts–their algae and/or cyanobacteria partners and absorb everything else they need from the air. This symbiosis helps lichens to survive in some of the harshest conditions on Earth — from scorching deserts to the freezing poles. They have even been taken up to the International Space Station, exposed to the vacuum of space and survived!
The particular group that pixie cups and their relatives belong to have what is called a fruticose growth form. They grow upright with little branches looking like tiny trees. In fact one species of reindeer lichen is commonly used as trees for model railroads. These branches are composed of three layers-a fungal outer cortex made of densely-packed fungal cells that serve to protect the inner layers. A middle layer is composed of the photobiont-algal cells wrapped with a net-like array of fungal cells. This is where the fungi and algae exchange sugars and nutrients. An inner medulla layer composed of loosely packed fungal cells runs up the center of the ‘trunk’ and ‘branches’ of these little trees and is thought to help support them.
In addition to being cute, these little lichens provide a host of ecosystem services-they provide food and shelter for wildlife. White-tailed deer eat British soldiers and moose will graze on reindeer lichen. Small mammals, snails and some insects also eat these lichens. High in carbohydrates, they are a particularly important food source in winter when other foods are scarce. Insects shelter beneath them and many species of birds and squirrels use them as nesting materials.
Winter is a great time to get outside and look for signs of life…tracks in the snow, the chirp of a bird from the undergrowth and these tiny lichens with their seasonal colors - hardy little creatures able to survive in the harshest of conditions.
Susan Pike, a researcher and an environmental sciences and biology teacher at Dover High School, welcomes your ideas for future column topics. Send your photos and observations to spike3116@gmail.com. Read more of her Nature News columns online at Seacoastonline.com and pikes-hikes.com and follow her on Instagram @pikeshikes.