FLORA 07 THE DISTRICT OP COLUMBIA. 45
P. OVARY 1-CELLED
14. POLYPODIUM L
Plants grayish beneath, the lower surface of the blades very densely covered with pale dark-centered peltate scales; sori small, sunken 1, P. polypodioides.
Plants green, the blades devoid of scales; sori superficial 8. P. vulgare.
1. Polypodium polypodioides (L.) flitchc. Gray polypody. Resurrection fern.
Flat mossy rocks or tree trunks; gorge of the Potomac below Great Falls, Maryland side, the only locality. Summer. Pa. to Iowa, southward to the Gulf states and trop. Amer. generally. (P. incanum Swartz.)
2. Polypodium vulgare L. Polypody.
Rocks or rocky banks; common along the upper Potomac and found in a few other localities. Summer. Eastern N. Amer.; also in Eur.
15. WOODS1A R. Br.
1. Woodsia obtusa (Spreng.) Torr.
Rocky banks and shaded cliffs; common, especially along the upper Potomac and the canal. Summer. Eastern N. Amer.
16. FILIX Adans. Bladder fern.
Blades very narrowly triangular-lanceolate, the apex long-tapering to a slender tip, usually bearing numerous fleshy bulblets beneath 1. P. bulbifera.
Blades broadly lanceolate, slightly narrowed at the base, the apex short-pointed;
bulblets wanting g. p. Iragilis.
FLORA 0? THE DISTRICT OF COLUMBIA. 57
1. Filix lralblfera (L.) Underw.
Shaded talus of cliffs; Virginia side of the Potomac in the region opposite Cabin John; very rare. Newf. to northern Ga., westward. (Cystopteris bvXH/era Bernh.) 2. Filix fragilis (L.) Underw. Brittle pern.
Shaded alluvial flats, rocky elopes, and moist woods; abundant in many localities, principally along the Potomac; common. Summer. N. Amer. generally; nearly cosmopolitan. (Cystopteris fragilis Bernh.)
17. DBYOPTEBIS Adans.
Indusia wanting; blades triangular, usually broader than long; pinnae adnate to the irregularly winged rachis. 1. D. hexagonoptera.
Indusia present; blades linear-lanceolate or narrowly oblong to ovate, much longer than broad; pinnae sessile, the rachis not winged.
Rootstocks very slender, widely creeping, nearly naked; fronds winter-killing, membranous; veins simple or once forked.
Lower pinnae gradually decreasing in size, the lowest ones minute.
8. D. noveboracensis.
Lower pinnae scarcely smaller than those above.
Fertile veins simple ...3. D. simulate.
Fertile veins once forked 4. D. thelypteris.
Rootstocks stout, short-creeping to erect, conspicuously scaly; fronds mostly ever- green, of firm texture; veins mostly 2 or more times forked.
Blades leathery; sori very much nearer the margins than the midribs of the seg- ments 5. D, marginalia.
Blades firm, but not thick and leathery; sori about midway from midrib to margin or nearer the midrib.
Fertile leaves very rigidly erect, tall and slender, long-stalked, the blades linear-oblong to narrowly lanceolate; sterile leaves short, spreading.
8. D. cristata.
Fertile and sterile leaves mostly ascending or spreading, the blades much broader, mostly oblong to ovate.
Basal scales thick, shining, dark chestnut-colored 7. D. goldiana.
Basal scales thin, membranous, dull light brown.
Pinnae deeply pinnatifid only, the few coarse lobes or divisions all adnate and distinctly joined, the wing very broad toward the tip.
8. D. elintoniana.
Pinnae essentially pinnate, at least the basal segments free, the others mostly constricted, joined by a faint wing or not.
Pinnules oblong to oblong-ovate, obtuse or at most acutish.9. D. boottii.
Pinnules mostly oblong-lanceolate, acute.
Pinnae oblique to the rachis, the basal ones distant, broadly triangular;
pinnules obliquely incised, the lobes with curved spinelike teeih;
indusia without glands 10. D. spinulosa.
Pinnae at right angles to the rachis, the basal ones ovate, strongly unequal-sided; pinnules pinnately divided, the segments with spreading teeth; indusia glandular .11, D. intermedia.
1. Dryopteris hexagonoptera (Michx.) G. Chr. Beech pern.
Dryish or well-drained open deciduous woods; abundant. Midsummer. Eastern N. Amer. (Phegopteris hexagonoptera F6e.)
8. Dryopteris noveboracensis (L.) A. Gray. New York fern.
Moist low woods and thickets; abundant. July. Eastern N. Amer. (Aipidium noveboracmse Swartz.)
i
8. Dryopteris Simulata Davenp. Massachusetts fern.
Woodland swamps; Hollywood Swamp and near Suitland; reported also from one or two other stations. Late summer. Me. to central N. Y. and Md.
4. Dryopteris thelypteris (L.) A. Gray. Marsh fern.
Marshes and low thickets, especially along streams; common. Midsummer.
Eastern N. Amer. (Aspidium thelypteris Swartz.)
5. Dryopteris marginalis (L.) A. Gray. Marginal shield-fern.
Rocky hillsides in rich woods; common, chiefly along the upper Potomac. July.
N. S, to Br. Col., south to Ga. and Okla. (Aspidium marginals Swartz.) 6. Dryopteris crlstata (L.) A. Gray.
Swamps and moist or boggy woods; common. July. Newf. to Va. and Ark., north- westward. (Aspidium cristatum Swartz; A. fWx-mas of Ward 's Flora.)
7. Dryopteris goldiana (Hook.) A. Gray. Goldie's fern.
Rich deciduous woods; several stations along the upper Potomac, both sides; rare.
N. Br. to Minn, and N. 0. (Aspidium goldianum Hook.)
8. Dryopteris cllntoniana (D. G. Eaton) Dowell. Clinton's fern.
Boggy woods; Lincolnia; very rare. Me. to Wis., south to N. C. (D. cristata zlintoniana D. C. Eaton.)
9. Dryopteris booth* (Tuckerm.) Underw. Boott's fern.
Moist wooded ravines; several localities, mostly in runs of the upper Potomac.
Summer. N. S. to Minn, and Va. (Aspidium boottti Tuckerm.)
Now usually regarded as a hybrid between D. cristata and Z>. intermedia.
10. Dryopteris spinnlosa (Muell.) Kuntze.
Rich low woods; common throughout the range. Summer. Newf. to Va., north- westward. (Aspidium spinulomm Muell.)
11. Dryopteris intermedia (Willd.) A, Gray. Wood fern.
Moist or dryish woods; fairly common. Summer. Newf. to Wis., south to N. C.
(Aspidium spinulosum intermedium D. C. Eaton.)
Besides Dryopteris boottii the following hybrids have been collected:
Dryopteris cristata X marginalis Davenp. Two collections, near Great Falls, Va. (Dowell).
Dryopteris goldiana X marginalis Dowell. Woods near Kensington (Dowell),
Marsilea quadri/olia L. was accidentally introduced in 1880 at Government Fish Ponds, since filled; it has perhaps escaped to the river. Native of Eur. and Asia;
possibly native at Bantam Lake, Conn., thence widely introduced from Mass. to Md.
6, EQUISETACEAE. Horsetail Family,
l. equisetum L.
Stems annual and of two kinds, the fertile appearing in spring and early withering, the sterile ones with whorls of numerous branches .1. E. arvense.
Stems perennial, evergreen, alike, without whorls of branches 2. E. praealtum.
1. Equisetum arvense L. Horsetail.
Sandy or alluvial soil; common. Early spring. Temperate N. Amer. generally, north of Mex.; also in Eur. and Asia.
2. Equisetum praealtum Raf. Scouring-bush.
Alluvial banks of the Potomac and tributary streams; occasional patches, but not K>ommon. U. S. generally. (E. robuslum A. Br,; E. hyemale of Ward's Flora.)
FLORA OF THE DISTRICT OF COLUMBIA. 59
6. LYCOPODIACEAE. Club-moss Family.
1, LYCOPODIUM L. CLUB-moss.
Spore cases borne in zones along the stem, in the axils of ordinary leaves,
1, L, lucidulum.
Spore canes borne in terminal conelike spikes.
Plants without leafy aerial branches, the long-stalked fertile spikes arising directly from the prostrate creeping leafy stem.
Stems short-creeping, the leaves of two kinds, arranged in 4 rows, spreading;
stalks of the fertile spikes very slender, with minute scattered bracts.
£. L. Carolinian um.
Stems wide-creeping, the numerous leaves alike, slender, curved upward;
stalks of fertile spikes stout, with numerous slender incurved overlapping leaves 8. L. adpressnm.
Plants with numerous erect or ascending leafy branches, the spikes terminal on some of these.
Leaves of the ultimate branches very slender, spreading, arranged in 6 or more rows.
Stems running horizontally deep in the ground, the few distant aerial branches upright and treelike, with numerous bushy branches; leaves in 6 or 8 rows 4. L. obscurum.
Stems prostrate, creeping many feet over the ground, branching horizontally, with numerous very leafy upright branches; leaves in many rows.
6. 1. clavatum.
Leaves of the ultimate branches minute, mostly imbricate, adnate and decur- rent, arranged in 4 rows.
Ultimate leafy branches strongly flattened; leaves of the under row smrller than the others and of different form 6. L. complanatum flabelUfotme.
Ultimate leafy branches much narrower, appearing less flat; leaves of the under row slightly smaller than the others but of similar form.
7. L. tristachyrun.
1. Lycopodium lucidulum Michx.
Cold damp woods and springy wooded banks, sometimes in beds of sphagnum;
infrequent, though of general distribution. Eastern N. Amer, 2. Lycopodium carolinianum L.
Cold sphagnum bog of white gravel and sand; a single locality known, Prince Georges County. N. J. to the Gulf states; a Coastal Plain plant.
3. Lycopodium adpressnm (Chapm.) Lloyd & Underw,
Bogs and low open fields, often in running water; abundant at several localities east of Washington. N. Y. to the Gulf states; mainly coastal.
4. Lycopodium obscurum L. Ground pine.
Moist woods and thickets; several scattered localities; not very common. Newf, to Alaska, south to Ga.; also in Asia. (L. den^roidewn Michx.)
4, Lycopodium clavatum L. Running pine.
Moist thickets and pine woods; apparently rare; Lanham; Sandy Springs; Merrifield.
Most of N. Amer.; also in Eur. and Asia.
6. Lycopodium complanatum flabellifonne Fernald. Christmas green.
Damp woods and thickets; fairly common. N, S. to Minn,, south to Va. (Typical L, complanatum ranges from Me. northward.)
7. Lycopodium tristachyum Pursh. Christmas green. Ground pine.
Low damp woods and thickets; not uncommon. Eastern U. S, (L. chamaeq/paris- atw A. Br.; L. complanatum sabinaefolium of Ward's Flora.)
7, SELA0IHEELACEAE. Selaginella Family.
1. SELAGINELLA Beau v.
Leaves very numerous, alike, appressed, widely overlapping, many-ranked, linear- lanccolate, ending in a slender whitish awn .1, S. rupestris.
leaves few, of 2 kinds, 4-ranked, spreading in 2 planes, ovate, acute or cuspidate.
2, S. apoda.
1. Selaginella rupestris (L.) Spring.
JExposed rocky bluffs; found only in vicinity of Great Falls, both aide.* of the river.
Ont. and eastern U. S.
2. Selaginella apoda (L.) Fernald.
Low moist situations, usually in partial shade; common. Me. to the Gulf states, westward. (S. apw Spring.)
8. ISOETACEAE. Quill wort Family.
1. ISOETES L. Quillwort.
Leaves 50-100, erect, 30-60 cm. long, with bast bundles 1. I. engelmanni valida.
Leaves 10-30, spreading or recurved, 3-25 cm. long, without bast bundles.
8. I. saccharata.
1. Isoetes engelmanni valida Engelm.
Temporary pools among rocks; Virginia shore of the Potomac, between Sandy Land- ing and Great Falls; rare. N. J, to Va.
2. Isoetes sacohaiata Engelm.
Shallow water between tides, on gravel and sand; banks of the Potomac at Fourmile Run, Hunting Creek, and Mount Vemon; not uncommon. Maes, to Va.
Extremely variable, several forms having been described.
9. PINACEAE. Fine Family.
Leaves scalelike or awl-shaped, opposite 4. JUNIPERUS.
Leaves linear, needle-like.
Leaves in fascicles 1. FINUS.
Leaves solitary.
Leaves stiff, about 10 mm. long, obtuse, persistent, dark green above, pale beneath; cones oblong, 2 cm, long or more, the scales rounded...2. TSTJOA.
Leaves slender, about 15 mm. long, acute, deciduous, light green on both faces;
cones globose or nearly so, the scales thick, woody 8. TAXODIUM.
1. PINTJS L. Pine.
Leaves 5 in a fascicle; cones more than 9 cm. long, maturing the first year, the scales without bristles 1. P. strobus.
Leaves 2 or 3 in a fascicle; cones less than 9 cm. long, maturing the second year, each scale bearing a bristle near the apex.
Leaves 3 in a fascicle.
Leaves 7-12 cm. long; cones ovoid, 3.5-7 cm. long 2. P. rigida.
Leaves 19-24 cm. long; cones oblong, 7-12 cm. long 3. P, taeda.
Leaves 2 in a fascicle.
Leaves slender, about 1 mm. in diameter, 6 cm. long or more 4. P. echinata.
Leaves stout, about 2 mm. in diameter and 4 cm. long.
Cone scales tipped with a slender straight fragile prickle 5. P. virginiana.
Cone scales tipped with a thick curved woody persistent prickle.
6. P. pungens.
FLORA OF THE DISTRICT OF COLUMBIA. 61
1. Finns strobus L. White riKE.
Sparingly on high ground toward Rockville; also reported from Turkey Bun, Barnes*
ville, and Occoquan. N orthern states, southward in the mountains to Ga. Also in cultivation.
Pinus exceha Wall., the Himalayan pine, is frequently cultivated. It is a hand' some tree similar to P. strobus, but with leaves 15-20 cm. long,
2. Plans rigida Mill. Pitch pine.
Sandy soil, scattered among Pinus virginiana. Eastern N. Amer.
3. Finns taeda L. Loblolly pine.
Found sparingly near our eastern limit; a few trees near Leland Station above Upper Marlboro; common along the Patuxent near the bay. A handsome tree, characteristic of the Coastal Plain from southern N. J. to Tex.
4. Finns echinata Mill. Yellow pine.
Sparingly among Pimm virginiana in the southern counties of Maryland; west of Mount Vernon. Eastern U. S. (P. mUi* Mkhx.)
5. Finns virginiana Mill. Scrub pine.
Our characteristic pine, forming forests in sandy soil. Eastern U. S„ (P. xnopt Ait.)
6. Finns pungens Lamb. Table-mountain pine.
A few trees in Hock Creek Park and on the bluffs of the Virginia shore of the Potomac above Cabin John. In the mountains, particularly along the ridges, from western
N. J. to Ga.
Pinus tylvestris L., the Scotch fir, is common in cultivation. It is readily distin- guished in its young state from Pinus virginiana by its bluish green young leaves and by the absence of bloom on its branchlets, a character conspicuous in our native tree. In America this tree is known under the name Scotch pine, though the European vernacular name is fir, which is applied properly to Pinus gylvestri* and
not to species of Abies.
Pinus austriaca Hoess, the Austrian pine, is extensively cultivated. It is readily recognized by its stiff dark green leaves, 12-16 cm. long, which are marked by 10 or
11 resin ducts in the parenchyma.
2. TSUGA Carr.
1. Tsnga cauadensis (L.) Carr. Hemlock.
Virginia shore of the Potomac above Cabin John; abundant at Occoquan. Northern states, south to Va.
3. TAXODIUM L. C. Rich.
1 Tarodium distlchum (L.) L. C. Rich. Bald cypress.
Swamps and along rivers; south of Bowie; near Marshall Hall. Southern states, north to N. J.
4. JUNTPEBTJS L. Juniper.
1. Jtwlperus virginiana L. Red cedar.
Common along the bluffs of the Potomac, in fields, and along roads; often planted. * Eastern N. Amer.
The leaves are of 2 kinds, scalelike on the mature trees and subulate on the young growth.
Juniperut communis L., the juniper, cultivated in this region but native farther north, is distinguished by its verticillate subulate leaves, 10 mm. long or more.
10, TYPHACEAE. Cat-tail Family.
1. TYPHA L. Cat-tail,
Staminate and pistillate portions of the spike distant; leaves 5 mm. wide.
1. T. angustilolfa, Staminate and pistillate portions of the spike contiguous; leaves 10 mm. wide.
2. T. latiiolia
1. Typha angustifolia L.
Marshes and wet places, forming colonies, Eur., Asia, and N. Amer. north of Mex.
2. Typha latiiolia L.
Marshes and wet places, forming colonies. Eur., Asia, and N, Amer.
11. SPARQ-ANIACEAE. Bur-reed Family,
1. SPARGANITTM L, BUR-reed.
Fertile flowers sessile; fruit broadly obovoid I. S. eurycarpum.
Fertile flowers short-pediceled; fruit fusiform.
Inflorescence simple 2. S. americanum.
Inflorescence with 1 or 2 weak branches from lower axils.
2a. S. americanum androcladum.
1. Sparganium eurycarpum Engelm,
Frequent in swamps and marshy margins of streams. Fr. July-Aug. Widely dis- tributed in N. Amer.
8. Sparganium americanum Nutt.
Frequent in the same situations as the last, but usually in shallower water. June- July; fr. Sept.. Eastern N. Amer. and Asia.
3a. Sparganium americanum androcladum (Engelm.) Fern. & Eamcs.
Habitat and range same as for the species. (S. androcladum {Morong; S, simplex androcladum Engelm.)
12. POTAHOGETOlfACEAE. Pondweed Family.
Leaves alternate; fruit subgloboae, short,-beaked; flowers perfect.