Guide to the Liverworts of North Carolina 9780822396888

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Guide to the Liverworts of North Carolina

Guide to the Liverworts of North Carolina DUKE UNIVERSITY PRESS

MARIE L. HICKS

Durham and London 1992

© I992 Duke University Press

All rights reserved Printed in the United States of America on acid-free paper 00 Library of Congress Cataloging-in-Publication Data appear on the last printed page of this book.

Contents

Acknowledgments vii 1

Introduction

3

2

Artificial Keys to Genera

3 Species Descriptions Literature Cited

14

2I

209

Appendix. Alphabetic List of Hepaticae and Anthocerotae of North Carolina Glossary

2I

5

Distribution Maps Index

237

223

211

Acknowledgments

This book evolved as a response to students' need for a simple guide for the identification of liverworts. Over the years I have had encouragement from students, colleagues, and family and for that I am grateful. Many individuals are due special thanks. Among them, for their encouragement and advice, K. S. Renzaglia of East Tennessee State University, D. K. Smith, K. D. McFarland, A. S. Heilman, and Paul C. Davison of the University of Tennessee. To Paul, I am particularly indebted for help with collecting as well as mapping of state distributions. I also thank 1. E. Anderson and B. D. Mishler of Duke University for making collections available and 1. W. Carpenter, K. H. Read, and 1. 1. Gaddy for help with field work. I am also indebted to R. C. Bruce and the Highlands Biological Station for support and use of facilities and to the Hesler Foundation of the University of Tennessee for support during I989 and I990. Thanks are also extended to the biology faculty of Appalachian State University for their support during an off-campus assignment. To Cindy, John, Jessica, and Marie, thank you for your good humor; it makes long trails short and cloudy days sunny.

Guide to the Liverworts of North Carolina

I

Introduction

Liverworts are small, mosslike plants that occupy moist microhabitats and usually form an inconspicuous part of the vegetation. Although of interest primarily to botanists, the variety of their form and the beauty of their symmetry, when observed under a lens, can be appreciated by anyone who takes the time to examine them. In North Carolina the liverwort, or hepatic, flora is relatively diverse because of the many habitats provided by the state's varied physiography-from the mountains, which support boreal plants, to the coastal plain, with its subtropical plants. The highest mountain peaks in eastern North America are found in western North Carolina, and the southern escarpment experiences very high rainfall, second only to the amounts received by the rain forests of the Pacific Northwest. Collection of hepatics in North Carolina has been sporadic over the years, and knowledge of their distribution within the state has accumulated gradually. Early botanists of the eighteenth and nineteenth centuries made a few collections of liverworts in North Carolina, mainly while seeking vascular plants. These were sent to Europe where they were identified or named. As a result, publications occasionally included some of North Carolina's liverworts. In 1904 Coker compiled a list of species known to occur in North Carolina (Coker 1904), and this list was added to by subsequent publications (Grout 1909; Andrews 1914; Standley 1914). Hugo L. Blomquist made many collections within the state during his tenure at Duke University, and these provided the basis for a comprehensive list of 143 taxa (Blomquist 1936). Subsequent collecting added to the number of species for the state (Blomquist 1939a, 1939b). Although Blomquist'S 1936 list included distributions, it did not have keys for identification. For many years the only comprehensive treatment for identification of North American liverworts was that of Frye and Clark (1937-1947), and some collections from North Carolina were included in the distributions given in that work. Important recent collections by R. M. Schuster, L. E. Anderson, and others have added substantially to our knowledge of liverwort distributions. Schuster's extensive collections from North Carolina arc included in his recent comprehensive volumes (Schuster 1966-1980), which treat the liverworts of eastern North America (including Greenland) in detail. The local guide to liverworts in the mountain counties of North Carolina (Hicks 1982) was based on plants from the mountains only.

Collections from the piedmont and coastal plain have been added to the present guide to complete the hepatic survey for the state. Since the publication of Blomquist's list, some plants have undergone nomenclatural changes, a few identifications have been changed, and new plants have been discovered in the state. This guide incorporates new information as well as providing keys and illustrations for identification of the state's liverworts. A distribution map or list by county is given for each taxon as well. In determining the distribution of species, the herbarium collections at Appalachian State University, Duke University, the University of North Carolina at Chapel Hill, and the University of Tennessee have been used, as well as the published reports by Schuster. For accuracy, the distributions are based on specimens in herbarium collections. * The distributions are by no means complete, and future collectors will most certainly add to them. The state's inventory now includes 195 taxa. Unfortunately, a few of the rarer liverworts may no longer survive in the state as the result of human "progress." The removal of trees all the way to the edges of creeks for farming and other activities has reduced many streams to silt-laden ditches and exposed delicate streamside plants to the drying effects of direct sunlight. Flooding of southern escarpment gorges by power companies and clearing of forcsts for mountain vacation dwcllings have resulted in destruction of habitat for some of the rarer species. City dwellers seeking escape to beautiful landscapes arc by their very numbers destroying the sources of the areas' attractiveness. Bryophytcs, with their green hues, clothe trees and rocks in moist habitats, softening an otherwise severe scene, but they are of little commercial value. Their importance in the ecosystem lies in their ability to hold large amounts of moisture within their cells, thereby slowing runoff. Because of their moistureholding capacity they arc also important as germination beds for seeds of other plants. The Area

North Carolina, with an area of 5712 square miles (33,755,500 acres!, is located in the humid temperate to subtropical region of the southeastern United States between 34 0 and 36.5 0 north latitude. The state can be divided into three physiographic provinces, which extend from the Atlantic coastal plain westward to the Blue Ridge and Smoky mountains (see fig. I). The Mountain Province of western North Carolina is part of the greater Appalachian Mountain system and is about 250 miles (400 km) long from the Virginia state line on the north boundary to the Georgia state line on the south. The width varies from about 15 to 50 miles (24-80 km). Thesc mountains include the Blue Ridge and the Smoky Mountain-Unaka Mountain ridges as well as other smaller ranges. The mountains of North Carolina include about twenty-five peaks with elevations exceed'To avoid redundancy and save space, the specimen numbers are not listed. Obviously, some common species in some counties will not be indicated, but without herbarium specimens as vouchers, these counties cannot be included in the distribution maps. 4

LIVERWORTS OF

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Figure

I

Map of North Carolina with county names.

ing 6000 ft (1850 mI. In North Carolina's Black Mountains, Mount Mitchell, with an elevation of 6684 ft (2050 m), is the highest peak east of the Mississippi River, and numerous other peaks exceed 5000 ft (1540 mI. The lower elevations in mountain valleys are at least 1200 ft (370 mI. The mountains are bounded on the east by the Brevard Fault Zone, which is responsible for the escarpment between the mountains and the piedmont below. Here the drop in elevation is rapid, and the escarpment is deeply cut by rivers, forming narrow gorges with spectacular waterfalls. These gorges are particularly rich in bryophytes. The mountains enjoy a moist, temperate climate with an average annual precipitation of 58-74 in (147-188 em). The southern escarpment receives the highest rainfall in the eastern United States-more than 100 in (245 cm) in some localities (Billings and Anderson 1966). The mountain peaks with spruce and fir as dominants support boreal vegetation, and the protected escarpment gorges are rich in cove hardwoods. Average July temperatures are generally 68°F (20°C) or below, and January temperatures are about 35°-39°F (2 °-4 0C). Snowfall is about 10 in (25 em) each year, with as much as 50 in (127 em) or more locally (Gade and Stillwell 1986). The Piedmont Province, a sloping plateau dissected by streams, is about 190 miles (300 km) wide at its maximum and has as its eastern boundary a line where the soft sedimentary rocks of the coastal plain change to harder crystalline basement rocks. This boundary, the Fall Line, is generally marked by rapids, cascades, and waterfalls on streams. Industrial development as well as major cities are found in this area. The piedmont, with elevations generally ranging from ISO to 1000 ft (45-300 m), is characterized by rolling hills. Its western edge ends at the escarpment, where there is a rapid rise from the upper piedmont, with elevations of 800-1200 ft (250-370 m), to elevations of 15003500 ft (450-900 mI. The upper piedmont has a few isolated outlying peaks with elevations to 2600 ft (800 mI. The area is underlain by gneiss, schist, volcanics, and granite. Granitic outcroppings and river valleys provide a variety of habitats for plants. While human activities, development, and farming limit habitats in this province, a wide variety of species can be found along streams, INTRODUCTION

in tracts of woods, and on granitic outcrops. July tempcratures average 75°79°F (24°-26°C), and January temperatures avcrage 40°-46°F (5 -S o C). Rainfall on the Piedmont is less than that of either the mountains or the coastal plain, averaging about 48 in (122 cm) annually. The Coastal Plain Province varies in width from IOO to 140 miles (160230 km) and comprises about 45 percent of the area of the state. It rises gradually from sea level to about 500 ft (150 m) in the Sandhills district. There is relief only along major rivers and at the Fall Line. The underlying rocks are soft sedimentary and the soils are mostly sandy, peaty, or clayey loam. Natural lakes, sandhills, and Carolina bays (shallow, swampy, peat-filled areas) are features providing interesting habitats for plants. Carolina bays are unique elliptical depressions that dot the coastal plain. Some are quite large and fill with water, forming lakes; others are peat-filled swampy or shallow depressions with typical bay vegetation. Liverworts in this province are found mostly on clayey soil, in freshwater swampy areas, along streams, and on tree bark. In the Outer Banks and Tidewater districts the number of species is limited by the plants' intolerance to even small amounts of salt spray. In spite of this, well-developed forests in protected areas support a surprising variety. Species here can be found on the bark of trees in leeward areas and around nonbrackish impoundments. In cypress swamps, which are common along rivers, trunks and knees provide habitat for a number of species. In these areas, some species of subtropical affinities reach their northern limit of distribution. The average July temperature on the coastal plain is about 80°F (27°C), and January temperatures are about 4So-46°F (7°-SOC). Precipitation varies from 50 to 64 in (127-162 cm) annually. 0

Liverwort Structure Hepatics are small plants ranging in shoot width from ahout 500 ~lln to several millimeters. The plants are either leafy or thalloid; the latter form, reminiscent of a lobed liver, gave the group its name several hundred years ago (from the Greek hepaticus, meaning "liver," and the Anglo Saxon wort or wyrt, meaning "plant" or "herb"). According to the belief of the time, these plants were useful in the treatment of liver ailments. Liverworts have traditionally been placed in the Class Hepaticae of the Division Bryophyta, which also includes mosses. (Recent authors have elevated the hepatics to a separate division, Hepatophyta.) The bryophytes are nonvascular; that is, they lack specialized internal tissue for the conduction of water and minerals. Liverworts differ from the mosses in having flattened, dorsiventral thalloid or leafy plant bodies. This growth form allows liverworts to lie close to the substrate where water can be absorbed and evaporation is minimized. The leaves of mosses, on the other hand, are spirally arranged around the axis of the plant. Although the group's name is derived from the thalloid form, leafy forms are much more common, comprising more than two-thirds of North Carolina's hepatics. Thalloid liverworts may be very thin and translucent or rather thick and 6

LIVERWORTS

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opaque. The central area of the thallus is thickened, forming a midrib region. Rhizoids, which anchor the plant, may be scattered on the ventral surface or restricted to the midrib region. In the Marchantiales the rhizoids are of two types: the usual smooth type and the "pegged" type, which has tubercules on the inside walls. Within the Marchantiales, the thallus may also have air pores or air chambers in the dorsal surface. The ventral surface may have scales as well as rhizoids. Thalloid forms in the Metzgeriales have a central axis with thin, laminar "wings" that are one cell or a few cells thick. Leafy forms grow from a single apical cell with three cutting faces; the faces give rise to three segments, each forming a leaf and part of the stem. As a result, the stem (or axis) bears three rows of leaves (unless reduction has taken place, in which case the ventral row may be reduced or missing). These leaves are one cell thick. Two of the rows are lateral; the third row is ventral (fig. 2). The ventral row of leaves, the underleaves, may be small and hidden among

Figure 2 (I I Ventral view of incubous arrangement of Calypogeia; (21 dorsal view of incubous Bazzania; (31 dorsal view of succubous Solenostoma; (41 Cephalozia with perianth and sporophyte; (sl Calypogeia with gemmiparous tip; (61 ventral view of complicate-bilobed Frullania.

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INTRODUCTION

7

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",',.," ": "

...~:.~.~

, . .,

", ',

4

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Figure 3 III Cells ending in a slime papilla; 121 gemmae; 13) cell with botryoidal oil bodies; 141 rhizoid with pegs; 15) cells with two granular oil bodies and large trigones; 161 cells with one large oil body per cell; 17) cells with granular oil bodies; 181 cells with granular oil bodies and large, bulging trigones; 19) spore with elater.

the rhizoids. Rhizoids occur on the ventral surface of the stem, scattered or in fascicles at underleaf bases; in a few plants they may arise from leaves. The arrangement and shape of the leaves is important in the identification of leafy forms. There are two principal ways in which the leaves overlap. In the incubous arrangement (fig. 2) the lower leaf overlaps the one above it. In the succubous arrangement (fig. 2) the upper leaf overlaps the lower. Some leafy forms have bilobed leaves that are sharply folded, giving the plant the appearance of having four or five rows of leaves (fig. 2). These types of leaves are termed complicatebilobed. The smaller lobes (lobules) are sometimes modified to form saclike structures that aid in retention of capillary water. Branching patterns in liverworts, like other vegetative characteristics, are useful in delimiting taxa. Two basic types occur: terminal and intercalary. The terminal branch originates at the apex of the plant from segments that result from the division of cells cut from the faces of the apical cell. Because the branch uses part of the segment, part of a leaf that would normally arise from the segment does not develop. As a result, the leaf at the base of a terminal branch origin will be a half leaf, either smaller than normal or with missing 8

LIVERWORTS

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lobes. Branches resulting from this process often diverge from the main stem at an angle of about forty-five degrees, giving the plant a dichotomous appearance. Intercalary branches arise from subsurface cells of the stem at later stages of maturity, and as they emerge, a collar forms at their base. These branches are often at right angles to the main stem. The cells in the leaves of most leafy forms contain (in addition to chloroplasts) one to many membrane-bound oil bodies of various sizes and shapes (fig. 3). These oil bodies can be observed with the light microscope, and the number, size, and shape are fairly constant for each species. In some genera (Radula, Leucole;eunea) the cell is crowded by one large oil body, and in a few others (Cephalozia, Nowellia) oil bodies are absent. Differences in oil body characteristics are helpful in identification, although this characteristic is best observed in fresh material because oil bodies disappear as cells die. Liverwort cell walls exhibit considerable variety in thickness and in the development of wall thickenings at cell angles. The wall thickness is affected somewhat by environmental conditions, although the ability to develop thickened walls is constant. Trigones are thickenings at cell angles (fig. 3); these are sometimes large and may bulge into the cell lumen. A few species also form supplementary nodular wall thickenings. In the leaves of a few species a vitta, a median strip of differentiated cells, may be found. These may be thicker walled and/or larger and more elongate than adjacent cells. The surface of leaf cells is usually smooth, but in a few taxa it is rough or may have low papillae or striae. The liverwort plant begins as a single cell, the spore (fig. 4). This spore grows into a green plant, the gametophyte, which produces gametes, or sex cells. The sex cells (sperm and eggs) are produced in special structures on the gametophyte plant. The egg is produced in a multicellular flask-shaped structure called the archegonium (fig. 4). The sperm cells are produced in an antheridium (fig. 4). In leafy forms the archegonia are found at the tips of shoots and are surrounded

Figure 4 Life cycle of Porella: (I) female shoot; (2) male shoot; (3) archegonium with egg; (4) antheridium with sperm; Is) sporophyte; (6) dehiscing capsule; (7) spore.

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4