Part 92

Spore-cases (_sporangia, thecae_) 6 or 7, adhering to the under side of the angled shield-shaped scales of the spike, 1-celled, opening down the inner side and discharging the numerous loose spores. To the base of each spore are attached 4 thread-like and club-shaped elastic filaments, which roll up closely around the spore when moist, and uncoil when dry.--Rootstocks perennial, wide-creeping, hard and blackish, jointed, often branched and sometimes bearing small tubers. Stems erect, cylindrical, hollow, jointed; the surface striated or grooved with alternate ridges and furrows, the cuticle in most species containing silica in the form of minute granules, rosettes, or tubercles; the joints containing besides the central air-cavity a circle of smaller hollows beneath the furrows and a set of still smaller ones beneath the ridges; the nodes closed and solid, each bearing instead of leaves a sheath which is divided into teeth corresponding in number and position to the principal ridges of the stem; stomata in the furrows, each with two pairs of guard-cells, of which the outer pair is marked with radiating lines of silica. Branches, when present, in whorls from the base of the sheath, like the stem, but without the central air-cavity. Prothallus green, formed upon the ground, often variously lobed, usually dioecious. (The ancient name, from _equus_, horse, and _seta_, bristle.)

Sec. 1. _Annual-stemmed, not surviving the winter._

[*] _Fruiting in spring from soft and rather succulent pale or brownish fertile stems, the sterile stems or branches appearing later, herbaceous and very different._

[+] _Fertile stems unbranched, destitute of chlorophyll and soon perishing; the sterile branching copiously._

1. E. arvense, L. (COMMON H.) Fertile stems (4--10' high) with loose and usually distant about 8--12-toothed sheaths; the sterile slender (at length 1--2 deg. high), 10--14-furrowed, producing long and simple or sparingly branched 4-angular branches, their teeth 4, herbaceous, lanceolate.--Moist, especially gravelly soil; very common. March--May. Rootstocks often bearing little tubers.--Var. CAMPESTRE, Milde, is a not uncommon state, in which the sterile stem bears a small fruiting spike at the summit. (Eu.)

[+][+] _Fertile stems when older producing herbaceous 3-sided branches, and lasting through the summer, except the naked top which perishes after fructification._

2. E. pratense, Ehrh. Sterile and finally also the fertile stems producing _simple straight branches_; sheaths of the stem with ovate-lanceolate short teeth, those of the branches 3-toothed; stems more slender and the branches shorter than in the last.--Mich. to Minn., and northward. April, May. (Eu.)

3. E. sylvaticum, L. Sterile and fertile stems (about 12-furrowed) producing _compound racemed branches_; sheaths loose, with 8--14 rather blunt teeth, those of the branches bearing 4 or 5, of the branchlets 3, lance-pointed divergent teeth.--Wet shady places; common northward. May. (Eu.)

[*][*] _Fruiting in summer; stems all of one kind, or the fertile contemporaneous with and like the sterile, equally herbaceous, producing mostly simple branches, or sometimes nearly naked._

4. E. palustre, L. Stems (10--18' high) slender, very deeply 5--9-grooved, _the ridges narrow and acute_, roughish, the lance-awl shaped teeth whitish-margined; branches always hollow, 4--7-angled, rather few in a whorl.--Wet places, Niagara River (_Clinton_), Wisc. (_Austin_), and northward. June. (Eu.)

5. E. littorale, Kuehlewein. Stems (8--18' high) slender, deeply 6--16-grooved, _the ridges rounded_, the teeth shorter than in the last, narrowly white-margined; branches often solid, 3--4-angled, 2--6 in a whorl.--Wet sandy shores, Vt. and N. Y., and northward.--Spores always abortive, whence the plant has been considered a hybrid, perhaps of E. arvense and E. limosum. July. (Eu.)

6. E. limosum, L. (Pl. 21, fig. 1--5.) Stems (2--5 deg. high) _slightly many-furrowed_, smooth, sometimes continuing unbranched, but usually producing ascending branches after fructification; sheaths appressed, with 10--22 (commonly about 18) dark-brown and acute rigid short teeth.--In shallow water; rather common.--Air-cavities none under the grooves, but small ones under the ridges. A form in which the branches bear numerous small spikes is var. POLYSTACHYUM, Brueckner. June, July. (Eu.)

Sec. 2. _Stems all alike, evergreen, unbranched, or producing a few slender erect branches; fruiting in summer. Central air-cavity of the stem very large._

[*] _Stems tall and stout (1{1/2}--4 deg. or even 6 deg. high), simple, or casually branched, evenly many-grooved; sheaths appressed._

7. E. hyemale, L. (SCOURING-RUSH. SHAVE-GRASS.) Stems 1{1/2}--4 deg. high, 8--34 grooved, the _ridges_ roughened by two more or less distinct lines of _tubercles; sheaths elongated_, with a black girdle above the base and a black limb; ridges of the sheaths obscurely 4-carinate, the teeth blackish, membranaceous, soon falling off.--Wet banks; common northward. Formerly in common use for polishing wood and metal. (Eu.)

8. E. robustum, Braun. Stems tall and stout (sometimes 8--10 deg. high and nearly an inch thick), 20--48-grooved, the _ridges_ roughened _with one line of transversely oblong tubercles; sheaths rather short_, with a black girdle at base and a black limb; ridges of the sheaths tricarinate, the blackish teeth soon falling off.--River-banks, Ohio and westward.

9. E. laevigatum, Braun. Stems 1--4 deg. high, rather slender, pale green, 14--30-grooved, the ridges almost smooth; sheath slightly enlarged upward, with a black girdle at the base of the mostly deciduous white-margined teeth, and rarely also at the base of the sheath; ridges of the sheath with one keel, or sometimes obscurely tricarinate.--By streams and in clayey places, Ohio to Minn., and westward.

[*][*] _Stems slender, in tufts, 5--10-grooved; sheaths looser._

10. E. variegatum, Schleicher. _Stems ascending_ (6--18' long), usually simple from a branched base, _5--10-grooved_; sheaths green variegated with black above, the 5--10 teeth tipped with a deciduous bristle.--Shores or river-banks, N. H. (Bellows Falls, _Carey_) and Niagara to Minn., and northward; rare. (Eu.)

11. E. scirpoides, Michx. _Stems very numerous in a tuft, filiform_ (3--6' high), _flexuous and curving, mostly 6-grooved_, with acute ridges; _sheaths 3-toothed_, the bristle-pointed teeth more persistent; central air-cavity wanting.--Wooded hillsides, N. Eng. to Penn., Minn., and northward. (Eu.)

ORDER 131. FILICES. (FERNS.)

_Leafy plants, with the leaves_ (fronds) _usually raised on a stalk or petiole_ (stipe), _rising from a_ (sometimes greatly elongated) _rootstock, separately rolled up_ (circinate) _in the bud, and bearing on the under surface or along the margin small reticulated sporangia, which at length split open and discharge the numerous minute spores. Prothallus green, above ground, normally monoecious._

SUBORDER I. Polypodiaceae. Sporangia collected in dots, lines, or variously shaped clusters (_sori_ or _fruit-dots_) on the back or margins of the frond or its divisions, cellular-reticulated, stalked, the stalk running into a vertical incomplete many-jointed ring, which by straightening at maturity ruptures the sporangium transversely on the inner side, discharging the spores. Fruit dots often covered (at least when young) by a membrane called the _indusium_ (or less properly the _involucre_), growing either from the back or the margin of the frond. (Plates 16--19.)

Tribe I. POLYPODIEAE. Fructification on the back of the frond, in round or roundish fruit-dots (_sori_) placed on the veins or at the ends of the veins, without indusium of any kind. Stipes articulated to the rootstock, leaving a distinct scar when separated. Veins free (not reticulated) in our species.

1. Polypodium. Sori round, in one or more rows, on each side of the midrib or of the segments of the frond.

Tribe II. GRAMMITIDEAE. Sori more or less elongated, without indusium, placed on the back of the frond, usually along the veins or near their extremities. Veins free in our species.

2. Notholaena. Sori short, of few rather large sporangia, placed near the tips of the veins; under surface of the frond usually either chaffy, woolly, or powdery.

Tribe III. PTERIDEAE. Fructification marginal or intramarginal, provided with a general indusium formed of the (either altered or unchanged) margin of the frond. Stipes not articulated to the rootstock. Veins free in all our species.

[*] Sporangia at the ends of the veins, on a reflexed portion of the margin of the frond.

3. Adiantum. Midrib of the pinnules marginal or none. Stipe black and polished.

[*][*] Sporangia borne on a continuous marginal vein-like receptacle, connecting the apices of the veins, and covered by a delicate whitish indusium formed of the reflexed margin.

4. Pteris. Midrib of the pinnules central. Stipe light colored.

[*][*][*] Sporangia at or near the ends of the unconnected veins, borne on the under surface of the frond; indusium various.

5. Cheilanthes. Sori minute, at the ends of the veins; indusium continuous or interrupted. Fronds mostly chaffy, woolly, or pulverulent, rarely smooth.

6. Pellaea. Sori on the upper part of the veins, distinct, or mostly forming a confluent submarginal band of sporangia. Indusium membranaceous, continuous, rarely wanting. Sterile and fertile fronds not very unlike; stipes dark colored; fronds smooth.

7. Cryptogramme. Sori roundish or elongated and extending far down the free veins, at first covered by the very broad continuous indusium, at length exposed and confluent. Sterile and fertile fronds very different; stipes light colored; fronds smooth.

Tribe IV. BLECHNEAE. Sori oblong or linear, borne on a veinlet parallel to the midrib, and covered with a special usually concave or arched indusium attached to the fruiting veinlet, and opening along the inner side.

8. Woodwardia. Sori forming a chain-like row each side of the midrib or central vein. Veins reticulated.

Tribe V. ASPLENIEAE. Sori more or less elongated, occupying one or both sides of oblique veins, covered by a special indusium which is attached by one side to the fertile vein, and is free on the other. Stipes not articulated.

9. Asplenium. Sori on the upper side or rarely on both sides of a veinlet. Veins free in all our species.

10. Scolopendrium. Sori linear, confluent in pairs, each pair appearing like a single sorus with a double indusium opening down the middle. Veins free.

11. Camptosorus. Sori oblong, variously curved, or some of them in opposite pairs. Veins reticulated.

Tribe VI. ASPIDIEAE. Sori round or roundish, on the back or rarely at the apex of the vein, with a special indusium, rarely naked. Stipes not articulated to the rootstock.

[*] Indusium obsolete or none.

12. Phegopteris. Sori round, rather small. Veins free in our species.

[*][*] Indusium evident, round or roundish, covering the sporangia, at least when young. Sterile and fertile fronds not very unlike. Veins free in our species.

13. Aspidium. Indusium flat or slightly convex, orbicular or round-reniform, fixed by the centre, opening all round the margin.

14. Cystopteris. Indusium convex, fixed by a broad base partly under the sorus, commonly reflexed as the sporangia ripen.

[*][*][*] Indusium obscure, irregularly semicircular. Fertile fronds much contracted and very unlike the sterile ones.

15. Onoclea. Sporangia on an elevated receptacle; divisions of the fertile frond pod-like or berry-like.

Tribe VII. WOODSIEAE. Sori round, borne on the veins; indusium fixed under the sorus, divided into segments or into slender filaments.

16. Woodsia. Small ferns with free veins. Indusium very delicate.

Tribe VIII. DICKSONIEAE. Sori roundish, marginal or submarginal. Indusium cup-shaped or two-valved, the outer portion composed of a reflexed lobule of the frond, or more or less united to it.

17. Dicksonia. Indusium in our species small, membranaceous, nearly globular. Frond elongated, decompound.

SUBORDER II. Hymenophyllaceae. Sporangia sessile on a bristle-like receptacle within a cup-shaped or bivalvular involucre, the ring transverse and complete. Fronds delicately membranaceous.

18. Trichomanes. Involucres funnel-form or cup-shaped.

SUBORDER III. Schizaeaceae. Sporangia ovate, sessile, having a complete transverse articulated ring at the apex, and opening by a longitudinal slit. (Pl. 19.)

19. Schizaea. Sporangia naked, fixed in a double row to the midrib of the narrow fertile segments. Sterile fronds rigid, simple or dichotomously branched.

20. Lygodium. Sporangia borne in a double row on narrow fertile segments, each sporangium seated on a separate veinlet, and provided with a special scale-like indusium. Fronds leafy, climbing.

SUBORDER IV. Osmundaceae. Sporangia naked, globose, mostly pedicelled, reticulated, with no ring or mere traces of one near the apex, opening into two valves by a longitudinal slit. Stipes winged at base and almost stipulate! (Pl. 19.)

21. Osmunda. Fertile pinnae or fronds very much contracted, bearing the abundant and large sporangia upon the margins of the very narrow segments. Veins free.

1. POLYPODIUM, L. POLYPODY. (Pl. 16.)

Fruit-dots round, naked, arranged on the back of the frond in one or more rows each side of the midrib or central vein, or irregularly scattered, each borne in our species on the end of a free veinlet. Rootstocks creeping, branched, often covered with chaffy scales, bearing scattered roundish knobs, to which the stipes are attached by a distinct articulation. (Name from [Greek: poly/s], _many_, and [Greek: pou~s], _foot_, alluding to the branching rootstock.)

1. P. vulgare, L. (Pl. 16, fig. 1--3.) Fronds evergreen, oblong, _smooth both sides_, 4--10' high, simple and deeply pinnatifid; the divisions linear-oblong, obtuse or somewhat acute, remotely and obscurely toothed; veins once or twice forked; _fruit-dots large, midway between the midrib and the margin_.--Rocks; common. July. (Eu.)

2. P. incanum, Swartz. Fronds evergreen and coriaceous, oblong, 2--6' high, _grayish and very scurfy underneath with peltate scales_, simply pinnatifid; the divisions oblong-linear, obtuse; _fruit-dots rather small, near the margin_; veins forking, free in the N. American plant!--Rocks and trunks of trees, Va. and Ohio to Ill., and southward. Aug.

2. NOTHOLAENA, R. Brown. CLOAK-FERN.

Fruit-dots roundish or oblong, placed near the ends of the veins, soon more or less confluent into an irregular marginal band, with no proper involucre. Veins always free. Fronds of small size, 1--4-pinnate, the lower surface almost always either hairy, tomentose, chaffy, or covered with a fine waxy white or yellow powder. (Name from [Greek: no/thos], _spurious_, and [Greek: lai~na], _a cloak_, the woolly coating of the original species forming a spurious covering to the sporangia.)

1. N. dealbata, Kunze. Fronds triangular-ovate, 1--3' long, 3--4-pinnate; rhachis and branches straight, black and shining; ultimate pinnules scarcely a line long, white and powdery on the lower surface.--Clefts of calcareous rocks, Mo., Kan., and southwestward. July--Aug.

3. ADIANTUM, L. MAIDENHAIR. (Pl. 17.)

Fruit-dots marginal, short, borne on the under side of a transversely oblong, crescent-shaped or roundish, more or less altered margin or summit of a lobe or tooth of the frond reflexed to form an indusium; the sporangia attached to the approximated tips of the free forking veins.--Main rib (costa) of the pinnules none (in our species), or at the lower margin. Stipes black and polished. (The ancient name, from [Greek: a] privative and [Greek: diai/no], meaning _unwetted_, the smooth foliage repelling rain-drops.)

1. A. pedatum, L. (Pl. 17, fig. 1--3.) _Frond forked at the summit of the upright slender stalk_ (9--15' high), the recurved branches bearing on one side several slender spreading pinnate divisions; pinnules numerous, short-stalked and obliquely triangular-oblong, entire on the lower margin, from which the veins all proceed, and cleft and fruit-bearing on the other.--Rich, moist woods. July.--A delicate and most graceful Fern.

2. A. Capillus-Veneris, L. _Fronds with a continuous main rhachis, ovate-lanceolate_, 9--18' long, often pendent, 2--3-pinnate at the base, the upper third or half simply pinnate; pinnules wedge-obovate or rhomboid, 6--12'' long, deeply and irregularly incised; veinlets flabellately forking from the base; involucres lunulate or transversely oblong.--Moist rocky places, Va. to Mo., and southward. (Eu.)

4. PTERIS, L. BRAKE or BRACKEN. (Pl. 17.)

Sporangia in a continuous slender line of fructification, occupying the entire margin of the fertile frond, and covered by its reflexed narrow edge which forms a continuous membranaceous indusium, attached to an uninterrupted transverse vein-like receptacle connecting the tips of the forked free veins.--Fronds 1--3-pinnate or decompound. (The ancient Greek name of Ferns, from [Greek: ptero/n], _a wing_, on account of the prevalent pinnate or feathery fronds.)

1. P. aquilina, L. (COMMON BRAKE.) Frond dull green (2--3 deg. wide), ternate at the summit of an erect stout stalk (1--2 deg. high), the widely spreading branches twice pinnate; pinnules oblong-lanceolate; the upper undivided; the lower more or less pinnatifid, with oblong obtuse lobes, margined all round with the indusium, which is really double in this species.--Var. CAUDATA, with the lobes very narrow and revolute, the terminal ones much elongated, is a southern form, which extends in a modified condition as far north as New Jersey.--Thickets and hillsides, common. Aug. (Eu.)

5. CHEILANTHES, Swartz. LIP-FERN. (Pl. 17.)

Sporangia borne on the thickened ends of free veinlets, forming small and roundish distinct or nearly contiguous marginal fruit-dots, covered by a mostly whitish and membranaceous, sometimes herbaceous, common indusium, formed of the reflexed margin of separate lobes or of the whole pinnule.--Low, mostly with 2--3-pinnate and hairy or chaffy, rarely smooth fronds, the sterile and fertile nearly alike, the divisions with the principal vein central. Some species with continuous indusium connect this genus very closely with the next. (Name composed of [Greek: chei~los], _a lip_, and [Greek: a)/nthos], _flower_, from the shape of the indusium.)

[*] _Fronds smooth, or at most hairy._

1. C. Alabamensis, Kunze. _Fronds smooth_, chartaceous (2--8' long), ovate-lanceolate, bipinnate; pinnae numerous, oblong-lanceolate; pinnules triangular-oblong, rather acute, often auriculate or lobed; _indusium continuous, rather broad, pale, and of firm consistence_.--On rocks, mountains of Va. to Ky., and southward.

2. C. vestita, Swartz. (Pl. 17, fig. 1, 2.) Fronds (6--15' high), lanceolate-oblong, hirsute, as are the brown and shining stipes, with _straightish prominently articulated rusty hairs_, twice pinnate; pinnae rather distant, triangular-ovate; pinnules oblong, crowded (2--4'' long), more or less incised, _the ends of the roundish or oblong lobes reflexed and forming separate herbaceous involucres_, which are pushed back by the ripened sporangia.--Clefts of rocks, Manhattan Island (_W. W. Denslow_) and N. J. to Ill., and southward.

[*][*] _Fronds woolly or tomentose._

3. C. tomentosa, Link. Fronds (12--20' high) lanceolate-oblong, densely tomentose with _slender and entangled whitish obscurely articulated hairs_, thrice pinnate; primary and secondary pinnae oblong or ovate-oblong; _pinnules distinct_, minute (1/2--1'' long), roundish-obovate, sessile or adnate-decurrent, the upper surface less woolly, _the reflexed narrow margin forming a continuous somewhat membranaceous indusium_.--Mountains of Va. and Ky.; thence west and southward.--Stipe and rhachis rather stout, brown, covered with narrow chaffy scales and whitish hairs.

4. C. lanuginosa, Nutt. Stipes slender, at first hairy, black or brown, shining; fronds (3--6' high) ovate-lanceolate, woolly with _soft whitish distinctly articulated flattened hairs_, becoming smoother above, twice or thrice pinnate; pinnae (5--6'' long) ovate, the lowest distant, the others contiguous; _pinnules crenately pinnatifid_, or mostly divided into minute and roundish densely crowded segments (1/2--1'' long), _the herbaceous margin recurved forming an almost continuous indusium_.--In dense tufts, on dry rocks and cliffs, Ill. to Minn., thence west and southward.

6. PELLAEA, Link. CLIFF-BRAKE. (Pl. 16.)

Sporangia in roundish or elongated clusters on the upper part of the free veins, distinct, or confluent laterally so as to imitate the marginal continuous line of fructification of Pteris, commonly covered by a broad membranaceous and continuous (rarely interrupted) general indusium, which consists of the reflexed and altered margin of the fertile pinnule or division. Small ferns, with 1--3-pinnate fronds, the fertile ones with narrower divisions than the sterile, but otherwise similar. Stipes generally dark-colored, smooth and shining. (Name from [Greek: pello/s], _dusky_, alluding to the stipe.)

1. P. gracilis, Hook. (Pl. 16.) Fronds smooth (3--6' high), _delicately membranaceous and slender_, of few pinnae, the lower ones once or twice pinnately parted into 3--5 decurrent divisions, those of the fertile frond oblong or linear-oblong, entire or sparingly incised; of the sterile ovate or obovate, crenate or incised; veins of the fertile fronds mostly only once forked.--Shaded calcareous rocks, Mass. to Minn., and northward; rare. July.--Rootstock very slender, creeping; stipes polished, brownish, darker and sparingly chaffy at base.

2. P. atropurpurea, Link. Smooth, except some bristly-chaffy hairs on the midribs and especially on the _dark purple and polished stalk_ and rhachis, 6--15' high; _frond coriaceous_, pale, once or below twice pinnate; the divisions broadly linear or oblong, or the sterile sometimes oval, chiefly entire, somewhat heart-shaped or else truncate at the stalked base; veins about twice forked.--Dry calcareous rocks; not common, but of wide range. July.--Rootstock short and stout; stipes clustered.

7. CRYPTOGRAMME, R. Brown. ROCK-BRAKE.

Fruit-dots roundish or elongated and extending far down on the free forking veins. True involucre or indusium none, the herbaceous margins of the fertile segments at first reflexed and meeting at the midrib, at length opening out flat and exposing the confluent sporangia.--Low ferns, with smooth, 2--3-pinnate fronds, the fertile ones taller than the sterile, and with much narrower divisions. (Name from [Greek: krypto/s], _hidden_, and [Greek: gramme/], _a line_, alluding to the lines of sporangia at first concealed by the reflexed margin.)

1. C. acrostichoides, R. Brown. Stipes densely tufted, straw-colored; fronds 2--3-pinnate (6--10' high); fertile segments stalked, linear or linear-oblong (3--5'' long), the sporangia in lines extending down the veins almost to the midrib, confluent when ripe and covering the under surface of the now fully opened segments; sterile fronds on much shorter stipes, with ovate or obovate decurrent and crenately toothed or incised segments. (Allosorus acrostichoides, _Sprengel_.)--On rocks, from L. Superior westward and northward.--Very near C. crispa of Eu.

8. WOODWARDIA, Smith. CHAIN-FERN. (Pl. 17.)

Fruit-dots oblong or linear, arranged in one or more chain-like rows on transverse anastomosing veinlets parallel and near to the midrib. Indusium fixed by its outer margin to the fruitful veinlet, free and opening on the side next the midrib. Veins more or less reticulated, free toward the margin of the frond.--Large ferns, with pinnatifid or pinnate fronds. (Named for _Thomas J. Woodward_, an English botanist.)

Sec. 1. ANCHISTEA. _Sterile and fertile fronds alike; veins forming only one row of meshes (areoles)._