Karl B McKnight is associate professor of biology at St. Lawrence University. Joseph R. Rohrer is professor of biology at the University of Wisconsin-Eau Claire. Kirsten McKnight Ward is a third-generation botanist/field guide author and professional artist. Warren J. Perdrizet is a recent graduate of St. Lawrence University with a BS in biology.

Common Mosses of the Northeast and Appalachians

By Karl B McKnight Joseph R. Rohrer Kirsten McKnight Ward Warren J. Perdrizet

Princeton University Press

Copyright © 2013 Princeton University Press
All right reserved.
ISBN: 978-0-691-15696-5

Contents

How to Use this Book……………………………..9Key Features…………………………………….10Key Features Path to the Keys……………………..16How to Look at a Moss…………………………….18Collecting Mosses………………………………..20What Are Mosses?…………………………………22Basic Structure of Mosses…………………………25Life History of Mosses……………………………26What Good Are Mosses?…………………………….28Acrocarps……………………………………….33Pleurocarps……………………………………..173Leafless………………………………………..317Peat Mosses……………………………………..321How to Use the Identification Keys…………………340Keys……………………………………………341Habitat Lists……………………………………380Moss Publications and Resources……………………384Moss Names………………………………………385Index…………………………………………..386

Chapter One

How to Look at a Moss

First, note its surroundings. Are you in an urban park, along a stream in a forest, in a bog? Is the moss growing on disturbed soil, the bark of a tree, a rock, a rotting log? Moss identification is often aided by knowing where the plant was growing.

Mosses grow everywhere, but that doesn’t mean every sprig is an ideal specimen to study. Look for healthy, homogeneous samples and avoid bedraggled, tiny samples that lack capsules and are growing intertwined with several species.

Many mosses look very different when wet versus dry. If possible, observe it in both conditions. Dry mosses can be moistened using a spray bottle, such as those used when ironing clothes or misting houseplants. Moisten the moss clump while intentionally keeping part of the clump dry by covering it with your hand as you mist. Then you can observe wet and dry plants side by side. If the moss is already wet, pull a few shoots from the clump; they will quickly dry in the air.

Pick a small sample and begin to tease apart individual shoots. Most mosses fall into one of two groups of different growth forms. Acrocarps generally stand upright, with many stems next to each other vertically and packed together into a clump or tuft. If the stem branches, it typically divides in two with the forks running side by side. In contrast, pleurocarps generally creep with their stems running along the substrate to which they are attached (soil, bark, rock, etc.), interweaving with other stems to form mats. Their branches split off at a right angle to the main stem. Growth form is the First Key Feature that will guide your identification. Study the text and illustrations on pp. 10-11 carefully before deciding on the growth form of your sample and moving on to examine the leaves.

That’s right — moss leaves are really small! You will need a hand lens of 7-20X to get a good look at them. Lower power lenses give a broader field of view, useful for initial examination, whereas higher power lenses provide the extra magnification needed to see fine detail.

To use your lens, look straight ahead and bring the lens close to your eye or glasses; then bring the moss sample up to the lens with your other hand. Play with the focus by moving the sample toward and away from the lens. Good light is essential. Tilt your head back to allow the light of the sky to shine through the leaf in order to search for a midrib and to silhouette teeth along the leaf margin.

Millimeter rulers are printed inside the front cover of the book and on the left sides of the identification key pages for convenience measuring leaves, but you might also want to carry a white plastic ruler with you.

The Second Key Feature to unlock the identity of your unknown moss is leaf shape. Most moss leaves fall along a continuum from hairlike through lance to ovate. The text and illustrations on pp. 12-13 and experience using our guide will help you become better attuned to where we drew the line between the various leaf shapes.

The Third Key Feature is the presence or absence of a midrib, a vein-like structure running lengthwise down the middle of some leaves. Most, but not all, acrocarps have leaves with midribs; leaves with and without midribs are common among pleurocarps. The text and illustrations on pp. 14-15 give tips in looking for midribs — not an easy task on leaves so small.

While you still have the leaf in front of your hand lens, check a few other characters. Examine the margin or edge of the leaf. Is it smooth or toothed? If toothed, do teeth cover the margin from apex to base, or is the margin toothed only along the upper half of the leaf? Does the edge appear to have a border distinct from the rest of the leaf blade? Typically a border is due to a rolled-down leaf margin, thus overlapping cell layers and looking dark.

Finally, search the clump or mat for sporophytes. A sporophyte consists of a spore-producing capsule elevated atop a stalk above the green, photosynthetic gametophyte of the moss. Although some species rarely, if ever, produce capsules, many mosses do so yearly. The shape and orientation of the capsule along with characters of its lid and hood are useful and sometimes essential features for identifying mosses.

Collecting Mosses

A reference collection is useful for teaching others about moss diversity as well as comparing new finds to specimens that you have previously identified. Refrain from collecting where prohibited, such as in national and state parks.

Because of their diminutive size, all you need is a small sample of moss, a teaspoon to tablespoon is about right. Never collect the entire clump or mat. Avoid mixed collections in which different species grow intertwined in a tuft or mat, and if available, include some plants with capsules. A pocket knife is handy for scraping mosses from rocks and bark, and for cleaning away soil. Dripping wet plants should be squeezed gently to remove excess water.

Place your specimen in a paper sandwich bag or a packet made from a folded sheet of paper (see illustrated instructions). Label the packet with information such as: the date, geographic location, habitat (forest, bog, field, etc.), and substrate (rock, soil, bark, etc.) on which the moss was growing. Once you have identified the moss, record its name on the packet.

After returning from the field, open your packets and spread your specimens out to dry. Left moist, they will become moldy, which is why plastic bags are acceptable only for very short-term storage. The dried specimens can be kept in shoeboxes and organized as desired.

What Are Mosses?

Most of us as children learn iconic figures for a tree, a bird and a flower. With maturity we learn to recognize more than one species in each of these categories. Not so with mosses, despite their ubiquity and accessibility. The book you are holding is a celebration of moss species diversity and an attempt to help you discover a larger world at your feet and fingertips. But first it is necessary to resolve some common misconceptions regarding what precisely is and is not a moss.

Spanish moss is not a moss. This common name refers to both a flowering plant of the pineapple family and a lichen, which is a composite organism made of a fungus and a photosynthetic alga.

Reindeer moss is not a moss. It is a lichen. Scratch this lichen, and you will find a thin line of green algae beneath the outermost layer of white fungi.

Other lichens are not mosses, though often mistaken for them.

Clubmosses are not mosses. They are spore-producing vascular plants with a life cycle similar to ferns.

Green algae are not mosses even though many people use that word for the green, slimy plants in streams, ponds and swimming pools.

Liverworts are not mosses. If you find a small green plant that you thought was a moss but is not found in our book, you may have found a liverwort.

There are hundreds of liverwort species growing in eastern North America. Some liverworts are not very mosslike; instead they look like flat green ribbons. They may be irregularly lobed with rounded ends, and some have stalks with umbrella-like tops (used for reproduction).

But other liverworts are easily confused with mosses. They can have creeping, flattened shoots with leaves that spread outward on opposite sides and overlap like scales. Liverworts often have a third row of tiny, hidden leaves. The leaves are either circular or deeply divided into narrow lobes and never have a midrib. In comparison, most mosses have leaves that emerge from all sides of the stem, are of similar size, are usually pointed and can have a midrib. Liverwort capsules are short-lived and thus not as commonly seen as moss capsules. They open by means of four vertical slits instead of a circular lid typical of most mosses.

Peat mosses are mosses. You will find more than a dozen species described in this book.

And these are mosses:

So what are mosses?

Mosses belong to a branch of the tree of life that diverged from green algae about 500 million years ago and includes all the land plants. Like other land plants, mosses have a multicellular body, contain green chlorophyll, and make their living through photosynthesis. Using the energy of sunlight, they combine carbon dioxide and water to make the sugars that are used for metabolism and to build their stems, leaves, and reproductive structures. As an evolutionary line, the mosses split early from the main branch of plants that went on to develop sophisticated conducting tissues and reproductive structures like seeds and flowers. Thus, mosses are some of the oldest and simplest plants on Planet Earth.

What Good Are Mosses?

Many people wonder if you can eat moss. Mosses produce a variety of secondary compounds that make them unpalatable and mostly indigestible to humans and most other animals. The very chemicals that make them inedible also make them attractive sources of antibacterial, antifungal, and antiviral compounds as we seek out new medicines. Some mosses have even been shown to have anticancer properties. Mosses have been used as bandages in surgical dressings and to regulate blood clotting. The fact that mosses are not eaten by most insects has led to recent assays for insect repellant compounds. Mosses are built of complex carbohydrates that require more energy to digest than most animals would gain even if they could tolerate the unpleasant taste. However, in spite of the negative caloric value, in order to obtain anti-freeze chemicals that help keep cold muscles moving, reindeer will eat certain mosses during severe winters. Mosses are also regularly eaten by woodland lemmings and barnacle geese.

Although used in earlier centuries by humans for everything from fuel, to diapering babies, to filling chinks between rocks and timbers of houses, there is much less household use of moss today. Most economic use comes from a single genus, Sphagnum, the peat mosses. Because of its ability to retain water and slowly release it, peat moss is widely used in the horticultural trade. Moist peat moss is used to keep plants alive during shipping. Mixed into soil, it adds water-holding capacity and organic matter. Its ability to inhibit the growth of bacteria and fungi makes it an excellent medium for germinating seeds.

This antimicrobial activity has recently been used in the production of pool and spa filters made of peat moss. Large mats of pleurocarpous mosses are rolled up and removed from forests in the Appalachians and Pacific Northwest for decorative use in planters as well as packing materials for shipping. Moss gardening with living plants is becoming increasingly popular.

Mosses serve many unsung but essential roles in the living world. Mosses are some of the first colonists of tree bark, soil, and newly exposed rock. Moss spores or leaf fragments are blown or are washed into newly exposed areas, and because mosses obtain their mineral nutrients from rain and splashed or running water, they don’t need previously developed soil to live. In fact, mosses promote soil formation through physical and chemical weathering of rock and dirt. As mosses grow, bits of dust and humus collect among the stems, and as they die their decomposing bodies add to the developing soil. In arid areas they help stabilize soils.

Because mosses are small and can survive without being rooted in soil, they can grow where other plants cannot, such as on cliffs, boulders, steep hills, and tree trunks. Many have the ability to dry out but remain alive and dormant. When moistened by rain or even fog, they can quickly resume photosynthesis and other life processes until they dry out again. By growing where other plants cannot, mosses add to the total photosynthetic productivity of the earth on which all animals and fungi depend. The drought resistant properties of mosses are also being studied as we develop more drought-resistant crops.

Mosses absorb water from rainfall and runoff and hold it like a sponge in and around their stems and leaves. This water is then slowly released to the ground or atmosphere. Slow release of water reduces stream erosion and fluctuating lake levels. Mosses are also slow to release mineral nutrients thus permitting more gradual colonization and growth cycles in many ecosystems.

Mosses provide homes for countless small animals that underpin entire ecosystems. What does a bobcat eat? Rodents, birds, and snakes. What do snakes eat? Among other things, frogs. What do frogs eat? Insects. Where do some of those insects live? In clumps of moss. If there is less moss, it means there will be fewer insects, fewer frogs, fewer snakes, and fewer or perhaps no bobcats.

Mosses also are important in the global carbon cycle. As mosses grow, they absorb carbon dioxide and release oxygen. In northern climates where decomposition is slow because of cold temperatures, vast amounts of carbon are sequestered in peat bogs. If global warming causes the release of this stored carbon, we may find it ever more difficult to keep carbon dioxide levels in the atmosphere within reasonable limits.

Mosses are very sensitive to the chemical and physical surface where they grow, and thus act as inexpensive indicators of air pollution and other environmental contaminants. Mosses can tell us about levels of minerals, heavy metals, moisture, and pH of roadsides, sidewalks, building walls, soils, and tree bark. Other species of indicator mosses can tell us about some of the chemicals in the air we breathe.

Beautiful mosses are all around us. Whether hiking along the Appalachian Trail, swimming at the base of a waterfall, or walking an urban sidewalk, it is hard not to be seduced by velvety carpets of moss. Most are perennial and do not die back in winter. So if not covered by snow, they are available for study in all seasons. This book is an invitation to slow down, to look closely, and to learn about and come to love some of nature’s smallest plants. Enjoy!

Bartramia pomiformis

APPLE MOSS

Appearance: Dull yellow green to blue green, pillowy cushions. Stems are upright, 2–6 cm high, sparsely forked, densely clothed with hairlike curly leaves, and topped by apple-round capsules on slender stalks. When dry, leaves are loosely and irregularly curled and twisted; wet, the leaves straighten and are held at 60 degrees from stems. Stem bases are often matted with brown fuzz.

Leaves: Hairlike, 4–6 mm long, from a widened clasping base. Edges are curled under, slimming the leaves to a hairlike tip. Midrib extends to apex. Fine teeth along edge of top half of leaf.

Capsules: When young, bright green globes resembling tiny apples. At maturity 1–2 mm long, inclined or perpendicular to the 1–2 cm stalk, round when moist, but elongate and deeply furrowed when dry. The convex lid falls off, revealing red teeth.

Habitat: Soil or rocks, usually acidic though sometimes calcium-enriched. Prefers damp shaded sites such as cracks in cliffs or rock outcrops and banks of ravines or streams.

Similar Species

Dicranella heteromalla (p. 37) Hairlike leaves are 2–3 mm long and gently swept to one side and barely curled, wet or dry. Capsules are shaped like a white-wine glass.

Philonotis fontana (p. 125) Shares the globose capsules, but has shorter, triangular leaves, 1–2 mm long, that don’t contort when dry.

Tortella tortuosa (p. 77) Leaves lack teeth that are coiled when dry and curved like an S when wet, leaves are more lance-shaped than hairlike at tips.

Microscopic Features

Cells each have one low bump. Teeth on leaf edges are actually double-toothed.

Ditrichum pallidum

SAFFRON MOSS

Appearance: Small, upright, 3–6 mm tall, yellow-green moss with shiny, hairlike leaves which spread from stem slightly when wet and are curled up when dry.

Leaves: Hairlike, 3–5 mm long, with a tiny widened base. Midrib fills most of blade and is difficult to distinguish except at base. Edges are smooth.

Capsules: Cylindrical, 1–2 mm long, upright to somewhat inclined, becoming ridged when dry, with tannish pink hairlike capsule teeth and a long-beaked lid. Stalk is 1–4 cm, bright yellow.

Habitiat: Disturbed soils, especially sandy and dry _ elds or partly shady woodlands.

(Continues…)

Excerpted from Common Mosses of the Northeast and Appalachiansby Karl B McKnight Joseph R. Rohrer Kirsten McKnight Ward Warren J. Perdrizet Copyright © 2013 by Princeton University Press. Excerpted by permission of Princeton University Press. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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