OREGON STATE MONOGRAPHS Studies in Botany FRANK H. SMITII, Ph.D., Consulting Editor Aquatic Plants of the Pacific Northwest With Vegetative Keys STUDIES IN BOTANY Number 11 i Studies in Botany 1.Tuberales of North America, by Helen M. Gilkey 2.Developmental Morphology of Alpova, by S. M. Zeller 3.Paleoecology of Two Peat Deposits on the Oregon Coast, by Henry P. Hansen 4. Moss Flora of the Willamette Valley, Oregon, by Clara J. Chapman and Ethel I. Sanborn 5.Floral Anatomy of the Santalaceae and Some Related Forms, by Frank H. Smith and Elizabeth C. Smith 6.Septoria Disease of Gramineae in Western United States, by Roderick Sprague, Ph.D., Pathologist 7.Clavaria, the Species from Oregon and the Pacific Northwest, by Maxwell S. Doty 8. The Marine Algae of the Coos Bay-Cape Arago Region of Oregon, by Ethel I. Sanborn, and Maxwell S. Doty 9. Northwestern American Plants, by Helen M. Gilkey 10.Species of Selenophoma on North American Grasses, by Roderick Sprague, and A. G. Johnson 11. Aquatic Plants of the Pacific Northwest with Vegetative Keys, by A. N. Steward, La Rea Dennis, and Helen M. Gilkey ii Aquatic Plants of the Pacific Northwest With Vegetative Keys By ALBERT N. STEWARD Formerly Associate Professor of Botany Associate Botanist, Agricultural Experiment Station, Oregon State College LA REA J. DENNIS Instructor in Botany, Curator of Herbarium, Oregon State College HELEN M. GILKEY Professor Emeritus of Botany, Oregon State College STUDIES IN BOTANY NUMBER 11 OREGON STATE COLLEGE CORVALLIS, OREGON 1960 iii TABLE OF CONTENTS Page Key to Families 3 Descriptive Flora 19 Glossary 165 Bibliography 171 Index 173 PLATES Page Plate I 26 Plate II 37 Plate III 48 Plate IV 56 Plate V 73 Plate VI 83 Plate VII 93 PlateVIII 96 Plate IX 104 Plate X 110 Plate XI 116 Plate XII 120 PlateXIII 125 Plate XIV 134 Plate XV 138 Plate XVI 143 PlateXVII 147 Plate XVIII 152 Plate XIX 158 Plate XX 164 Printed at the College Press Oregon State College iv PREFACE With the support of the National Science Foundation, the late Dr. Albert N. Steward started work on vegetative keys to the aquatic plants of thePa- cific Northwest ; his untimely death in June of 1959 made it necessaryfor as- sociate authors to be named to continue the project. The area included in this study is Oregon, Washington, British Colum- bia, and Alaska. Considerable difficulty was encountered in preparing alist of plants to be included. An effort was made to include all true aquatics andalso species whose life cycle includes some stage that requires either the saturation of the substrate with water or the presence of an ambient aqueousmedium. The intent has been to exclude species occasionally found in moist places but equally at home in drier situations. In the Pacific Northwest the period of flowering and fruiting of aquatic plants is very short when compared to the long period of vegetative develop- ment experienced by a large proportion of the species.Many species appear not to flower every year but may appear prominently in the floravegetatively for ten to twelve months of each year. This situation makes it mostdesirable that the keys be constructed primarily upon vegetative characters.This has been the approach wherever possible in this study. Reproductive characters have often been given as secondary characteristics to supplementand strengthen the keys. Where species are not readily distinguishable vegetatively, inserts were made in the key making separations on reproductive characters. Numerous individuals have helped in the preparation of this manuscript ; to them the authors express their genuine appreciation.Special mention should be made of the National Science Foundation for making the studyfinancially possible; Dr. Roy A. Young, head of the Department of Botanyand Plant Pathology for encouragement and consideration; Dr. Harry K. Phinneyfor advanced testing of the key to families in his class and for valuable sugges- tions; Dr. Frank H. Smith for critical editorial and technical assistance;and Mrs. Catherine Davis Young for most of the detailed drawings. February 18, 1960 Aquatic Plants of the Pacific Northwest With Vegetative Keys KEY TO FAMILIES Page la.Plants not differentiated into true roots, true stems, true leaves, not possessing true vascular tissue, the plant body therefore a thallus ; gametophytic thallus often producing structures superficially resembling roots, stems, and leaves ; reproduction vegetative and/or by spores [BRYOPHYTA] 2a. Gametophytic thallus radially symmetrical; leaf-like structures scale- like and overlapping [MUSCI] 3a. Plants with long stem-like structures floating out from the point of attachment, green in color __species of Fontinalis and Dichelyma FONTINALCEAE 22 3b. Plants with rather short stem-like structures forming thin mats on rocks or soil, or the mats rarely floating; or forming dense cushion-like mats in bogs. 4a. Color of the plants grayish-green; a thick cushion-like mat in bogs Sphagnum SPHAGNACEAE 23 4b. Color of plants yellow-green, brownish, or nearly black ; thin mats covering rocks or soil, or the mats rarely float- ing in fresh water streams species of Leptodictyum, DrepanocladusandHygrohypnum HYPNACEAE 23 2b. Gametophytic thallus not radially symmetrical, but dorsiventral ;often conspicuously bilaterally symmetrical [HEPATICAE] Sa. Thallus flattened, expanded, green above, colorless beneath the upper layer containing air chambers, these generally opening to the ventral exterior by pores ; rhizoids of 2 forms, one smooth and thin-walled,the otherinternally roughened and thick- walled. 6a. Plants free-floating, at least at first ; generally less than 1.5 cm. in length; sporophytes embedded in notch of game- tophyte Ricciocarpus RICCIACEAE 19 6b. Plants not free-floating; usually much longer than 1.5 cm., often reaching 10 cm. or more; sporocarps borne on stalked receptacles Con- ocephalum and Marchantia MARCHANTIACEAE 19 5b. Thallus either flattened and expanded, or organized into a stem- like structure bearing 2 or 3 rows of leaf-like organs; green throughout ; rhizoids always smooth-walled. 7a. Thallus body simple, undulate-margined to somewhat lobed, more or less dichotomous, sometimes with stomatal slits ; capsule long, slender, sessile, 2-valved, stomata-bearing ANTHOCEROTACEAE 22 7b. Thallus body simple, branching pinnately, palmately, or dichotomously; or consisting of a simple or branching bi- laterally symmetrical axis bearing 2 lateral rows of gen- erally overlapping leaf-like organs ; neither air-chambers nor pores present; capsule stipitate, 4-valved, or rarely opening irregularly at the apex. 8a. Gametophyte simply thallose, with undulate or ob- scurely lobed margins, or deeply pinnatifid; capsule 4-valved, or opening irregularly. 9a.Plant body a pinnately-, palmately-, or dicho- tomously branchingthallus ; sporophytes borne on special short branches RICCARDIACEAE 20 3 4 AQUATIC PLANTS OF THE PACIFIC NORTHWEST 9b. Plant body varying from a simple thallus to a pinnate arrange- ment of irregular thallose plates along a central axis; sporo- phyte arising from the ventral surface of the axis PELLIACEAE 20 8b. Gametophyte consisting of a simple or branching cylindrical stem-like structure bearing 2 lateral rows (and often an additional ventral row) of generally overlapping, thin, bright green, leaf-like organs ;sporo- phytes borne at the ends of the main axes or their branches; capsule 4-valved. 10a. Leaf-like organs entire, or if lobed, the lobes similar LOPHOZIACEAE 20 10b. Leaf-like organs 2-lobed, the lobes dissimilar_ SCAPANIACEAE 22 lb.Plants typically differentiated into true roots, true stems, true leaves ; vascular tissue present ; plants reproducing by spores or seeds. Ila. Gametophyte and sporophyte independent at maturity ; plants reproduc- ing by spores [PTERIDOPHYTA] 12a. Plants free-floating;leaves 2-lobed, imbricate ;rootlets and sporocarps borne in pairs on the under surface Azolla filiculoides SALVINIACEAE 25 12b. Plants rooting in the subsoil ; not free floating. 13a. Vernation circinate (i.e. leaves coiled in the bud) ; leaf blades more or less expanded. 14a. Leaves with 4-parted clover-like blades ;or fili- form, without blades; sporangia in ovoid or globose sporocarps borne near the leaf bases.... MARSILEACEAE 25 14b. Leaves not clover-like or filiform;sporangia membranous, clustered on the dorsal surface of the leaves POLYPODIACEAE 24 13b. Vernation not circinate; leaves various. 15a. Leaf of 2 parts, a sterile portion and a spore- bearing spike OPHIOGLOSSACEAE 24 15b. Leaf scale-like or quill-like, not in 2 parts. 16a. Stems hollow, jointed; leaves scale-like, whorled EQUISETACEAE 27 16b. Stems short, not jointed; leaves quill-like, not whorled ISOETACEAE 28 11b. Gametophyte reduced and dependent upon the sporophyte; plants repro- ducing by seeds [SPERMATOPHYTA] 17a. Plants normally free-floating or submerged. 18a. Normally free-floating on or immediately beneath the water surface; plant consisting of a small round, oval, or oblong,oftenflattened,undifferentiatedthallus body, rootless or with one to several rootlets dangling from the lower surface; flowers, when present, almost microscopic, borne in minute spathes at base of the thallus LEMNACEAE 84 18b. Not free-floating; normally submerged or largely so, but rooting in the subsoil ; plant consisting of normal stem, leaves, and roots; leaves sometimes floating or raised above the water level. KEY TO FAMILIES 5 19a. Plants acaulescent, from stout creeping rhizomes ; petioles erect, blades float- ing or carried above the water surface Nuphar NYMPHAEACEAE 105 19b. Plants caulescent, mostly weak and flexuous ; leaves floating or submerged. 20a. Leaves peltate, floating, entire; the petiole, the lower surface of the blade, and the stems, all covered by a thick gelatinous layer; flow- ers axillary and solitary, purplish; carpels 4-18, separate, indehiscent in fruit CABOMBACEAE 105 20b. Leaves not peltate. 21a. Leaf blades not dissected into narrow divisions. 22a. Leaves whorled (sometimes appearing whorled, also, in Najas of NAJADACEAE). 23a. Stems conspicuously weak and flexuous ; leaves in whorls of 3 or 4 ; blades thin, with thick- ened midribs; perianth present, the tube elon- gated, pedicel-like HYDROCHARITACEAE 40 23b.