# An Illustrated Flora of the Northern United States, Canada and the British Possessions/Isoetaceae

Family 11.   Isoetàceae   Underw.   Native Ferns 104.   1881.
Quillwort Family.
Aquatic or marsh plants rooting in the mud, with a short buried 2-lobed or 3-lobed trunk (stem) sending out abundant roots and sending up a compact tuft of rush-like leaves. Sporanges sessile in the axils of the leaves, some containing megaspores (megasporanges), others microspores (microsporanges); the former germinate into prothallia bearing only archegones, the latter into prothallia bearing usually only a single antherid.
The family consists of the following genus only.

## 1.0

1.  Isòetes   L.   Sp. Pl. 1100.   1753..
Submerged, amphibious or uliginous plants with a cluster of elongated awl-shaped leaves rising from a more or less 2-3-lobed fleshy short stem, the leaves with or without peripheral bast-bundles, with or without stomata, bearing a small membranous organ (ligule) above the base. Sporanges sessile in the excavated bases of the leaves, orbicular or ovoid, the sides more or less covered with a fold of the inner side of the leaf-base (velum). The sporanges of the outer leaves usually contain spherical, mostly sculptured macrospores, those of the inner ones contain minute powdery usually oblong microspores. [Name Greek, taken from Pliny, apparently referring to the persistent green leaves.]
About 60 species, widely distributed. Besides the following 2 are known from the southern United States, 7 from the Pacific Coast and 2 from Mexico. Owing to their aquatic habitat and apparently local distribution, these plants are popularly little known. The spores mature in summer and autumn. Type species: Isoetes lacustris L.
Leaves without peripheral bast bundles. :
| | • | Leaves without stomata; plants submerged. | Leaves without stomata; plants submerged. | Leaves without stomata; plants submerged. | Leaves without stomata; plants submerged. | Leaves without stomata; plants submerged. | Leaves without stomata; plants submerged. | Leaves without stomata; plants submerged. | Leaves without stomata; plants submerged. | Leaves without stomata; plants submerged. |
| | | • | Leaves stiff and erect. | Leaves stiff and erect. | Leaves stiff and erect. | Leaves stiff and erect. | Leaves stiff and erect. | Leaves stiff and erect. | Leaves stiff and erect. | Leaves stiff and erect. | 1. | I. macrospora. |
| | | • | Leaves slender and mostly recurved. | Leaves slender and mostly recurved. | Leaves slender and mostly recurved. | Leaves slender and mostly recurved. | Leaves slender and mostly recurved. | Leaves slender and mostly recurved. | Leaves slender and mostly recurved. | Leaves slender and mostly recurved. |
| | | | • | Leaves about ½" in diameter. | Leaves about ½" in diameter. | Leaves about ½" in diameter. | Leaves about ½" in diameter. | Leaves about ½" in diameter. | Leaves about ½" in diameter. | Leaves about ½" in diameter. | 2. | I. Tuckermanii. |
| | | | • | Leaves at least 1½" in diameter. | Leaves at least 1½" in diameter. | Leaves at least 1½" in diameter. | Leaves at least 1½" in diameter. | Leaves at least 1½" in diameter. | Leaves at least 1½" in diameter. | Leaves at least 1½" in diameter. | 3. | I. hieroglyphica. |
| | • | Leaves with stomata; plants partially submerged, or emersed. | Leaves with stomata; plants partially submerged, or emersed. | Leaves with stomata; plants partially submerged, or emersed. | Leaves with stomata; plants partially submerged, or emersed. | Leaves with stomata; plants partially submerged, or emersed. | Leaves with stomata; plants partially submerged, or emersed. | Leaves with stomata; plants partially submerged, or emersed. | Leaves with stomata; plants partially submerged, or emersed. | Leaves with stomata; plants partially submerged, or emersed. |
| | | • | Leaves green. | Leaves green. | Leaves green. | Leaves green. | Leaves green. | Leaves green. | Leaves green. | Leaves green. |
| | | | • | Macrospores armed with spines. | Macrospores armed with spines. | Macrospores armed with spines. | Macrospores armed with spines. | Macrospores armed with spines. | Macrospores armed with spines. | Macrospores armed with spines. | 4. | I. Braunii. |
| | | | • | Macrospores without spines, merely crested or warted. | Macrospores without spines, merely crested or warted. | Macrospores without spines, merely crested or warted. | Macrospores without spines, merely crested or warted. | Macrospores without spines, merely crested or warted. | Macrospores without spines, merely crested or warted. | Macrospores without spines, merely crested or warted. |
| | | | | • | Leaves 3'-3' long; macrospores less than 550 μ in diameter. | Leaves 3'-3' long; macrospores less than 550 μ in diameter. | Leaves 3'-3' long; macrospores less than 550 μ in diameter. | Leaves 3'-3' long; macrospores less than 550 μ in diameter. | Leaves 3'-3' long; macrospores less than 550 μ in diameter. | Leaves 3'-3' long; macrospores less than 550 μ in diameter. | 5. | I. saccharata. |
| | | | • | Leaves 4'-8' long ; macrospores about 6ooμ in diameter. | Leaves 4'-8' long ; macrospores about 6ooμ in diameter. | Leaves 4'-8' long ; macrospores about 6ooμ in diameter. | Leaves 4'-8' long ; macrospores about 6ooμ in diameter. | Leaves 4'-8' long ; macrospores about 6ooμ in diameter. | Leaves 4'-8' long ; macrospores about 6ooμ in diameter. | Leaves 4'-8' long ; macrospores about 6ooμ in diameter. | 6. | I. riparia. |
| | | • | Leaves reddish, or rarely olive green. | Leaves reddish, or rarely olive green. | Leaves reddish, or rarely olive green. | Leaves reddish, or rarely olive green. | Leaves reddish, or rarely olive green. | Leaves reddish, or rarely olive green. | Leaves reddish, or rarely olive green. | Leaves reddish, or rarely olive green. | 7. | I. foveolata.. |
| • | Leaves with stomata and bast bundles. | Leaves with stomata and bast bundles. | Leaves with stomata and bast bundles. | Leaves with stomata and bast bundles. | Leaves with stomata and bast bundles. | Leaves with stomata and bast bundles. | Leaves with stomata and bast bundles. | Leaves with stomata and bast bundles. | Leaves with stomata and bast bundles. | Leaves with stomata and bast bundles. |
| | • | Aquatic, but usually inhabiting the water's edge, sometimes completely emersed. | Aquatic, but usually inhabiting the water's edge, sometimes completely emersed. | Aquatic, but usually inhabiting the water's edge, sometimes completely emersed. | Aquatic, but usually inhabiting the water's edge, sometimes completely emersed. | Aquatic, but usually inhabiting the water's edge, sometimes completely emersed. | Aquatic, but usually inhabiting the water's edge, sometimes completely emersed. | Aquatic, but usually inhabiting the water's edge, sometimes completely emersed. | Aquatic, but usually inhabiting the water's edge, sometimes completely emersed. | Aquatic, but usually inhabiting the water's edge, sometimes completely emersed. |
| | | • | Leaves from 12'-30' long; macrospores with convolute labyrinthine ridges. | Leaves from 12'-30' long; macrospores with convolute labyrinthine ridges. | Leaves from 12'-30' long; macrospores with convolute labyrinthine ridges. | Leaves from 12'-30' long; macrospores with convolute labyrinthine ridges. | Leaves from 12'-30' long; macrospores with convolute labyrinthine ridges. | Leaves from 12'-30' long; macrospores with convolute labyrinthine ridges. | Leaves from 12'-30' long; macrospores with convolute labyrinthine ridges. | Leaves from 12'-30' long; macrospores with convolute labyrinthine ridges. | 8. | I. Eatoni. |
| | | • | Leaves shorter; macrospores otherwise marked. | Leaves shorter; macrospores otherwise marked. | Leaves shorter; macrospores otherwise marked. | Leaves shorter; macrospores otherwise marked. | Leaves shorter; macrospores otherwise marked. | Leaves shorter; macrospores otherwise marked. | Leaves shorter; macrospores otherwise marked. | Leaves shorter; macrospores otherwise marked. |
| | | | • | Bast bundles only 4, except in some forms of I. Engelmanni. | Bast bundles only 4, except in some forms of I. Engelmanni. | Bast bundles only 4, except in some forms of I. Engelmanni. | Bast bundles only 4, except in some forms of I. Engelmanni. | Bast bundles only 4, except in some forms of I. Engelmanni. | Bast bundles only 4, except in some forms of I. Engelmanni. | Bast bundles only 4, except in some forms of I. Engelmanni. |
| | | | | • | Monoecious. | Monoecious. | Monoecious. | Monoecious. | Monoecious. | Monoecious. |
| | | | | | • | Macrospores coarsely crested. | Macrospores coarsely crested. | Macrospores coarsely crested. | Macrospores coarsely crested. | Macrospores coarsely crested. | 9. | I. Dodgei. |
| | | | | | • | Macrospores merely reticulated. | Macrospores merely reticulated. | Macrospores merely reticulated. | Macrospores merely reticulated. | Macrospores merely reticulated. | 10. | I. Engelmanni. |
| | | | | • | Polygamous; microspores rare. | Polygamous; microspores rare. | Polygamous; microspores rare. | Polygamous; microspores rare. | Polygamous; microspores rare. | Polygamous; microspores rare. | 11. | I. Gravesii. |
| | | | • | Bast bundles 4, with extra ones near periphery. | Bast bundles 4, with extra ones near periphery. | Bast bundles 4, with extra ones near periphery. | Bast bundles 4, with extra ones near periphery. | Bast bundles 4, with extra ones near periphery. | Bast bundles 4, with extra ones near periphery. | Bast bundles 4, with extra ones near periphery. | 12. | I. melanopoda. |
| | • | Terrestrial, or rarely growing near water's edge. | Terrestrial, or rarely growing near water's edge. | Terrestrial, or rarely growing near water's edge. | Terrestrial, or rarely growing near water's edge. | Terrestrial, or rarely growing near water's edge. | Terrestrial, or rarely growing near water's edge. | Terrestrial, or rarely growing near water's edge. | Terrestrial, or rarely growing near water's edge. | Terrestrial, or rarely growing near water's edge. | 13. | I. Butleri. |

### 1.1

* 1.  Isoetes macróspora  Durieu. Lake Quillwort.   Fig. 118.
* Isoetes macrospora Durieu, Bull. Soc. Bot. France, 11: 101. 1864.
* Isoetes heterospora A. A. Eaton, Fernwort Papers 8. 1900.
* Submerged or rarely above water in dry seasons; leaves 10-30, rigid, rather thick, scarcely tapering, dark or olive green, obtusely quadrangular, 2'-6' long; stomata none; peripheral bast-bundles wanting; sporange orbicular or broadly elliptic, unspotted; velum rather narrow; ligule triangular, short or somewhat elongated; macrospores 600-800 μ in diameter, marked all over with distinct or somewhat confluent crests, and bearing three converging ridges; microspores 30-46 μ long, smooth or papillose.
* In 1°-5° of water, Labrador to the Northwest Territory, south to eastern Massachusetts and New Jersey. Formerly confused with Isoetes lacustris L., of the Old World.

### 1.2

* 2.  Isoetes Tuckermáni  A. Br. Tuckerman's Quillwort.   Fig. 119.
* Isoetes Tuckermani A. Br. in A. Gray, Man. Ed. 5, 676. 1867.
* Isoetes Tuckermani borealis A. A. Eaton, Fernwort Papers 10. 1900.
* Isoetes Harveyi A. A. Eaton, Fernwort Papers 11. 1900.
* Submerged or rarely partly or wholly emersed during very dry seasons; leaves 10-40, very slender, tapering, olive-green, quadrangular, 2′–5′ long, without peripheral bast-bundles, the outer recurved; sporange oblong, mostly white, its upper one-third covered by the velum; macroscpores 440-785 μ in diameter, with wavy somewhat parallel and branching
* ridges on the upper half, separated by the three converging ridges, the lower covered with an irregular network; microspores 26-42 μ long, nearly smooth, or with minute spines.
* In ponds, Newfoundland to Massachusetts and Connecticut; clustered in shallow water.

### 1.3

* 3.  Isoetes hieroglyphica  A. A. Eaton. Warty Quillwort.   Fig. 120.
* Isoetes hieroglyphica A. A. Eaton, Fernwort Papers 10. 1900.
* Submerged with a bilobed trunk. Leaves 10-20, 2½′–3′ long, blunt at the apex, without stomata; sporange spotted with dark cells, covered one-third to two-thirds by the velum; macrospores 486-720 μ in diameter, polished, covered with bold vermiform, subconfluent and somewhat reticulated ridges, becoming naked near the equator; microspores 31-44 μ in diameter, distinctly verrucose.
* Nova Scotia to Quebec and Maine; usually growing in ponds and lakes.

### 1.4

* 4.  Isoetes Braùnii  Durieu. Braun's Quillwort.   Fig. 121.
* Isoetes Braunii Durieu, Bull. Soc. Bot. France, 11: 101.  1864.
* Isoetes echinospora var. Braunii Engelm. in A. Gray, Man. Ed. 5, 676.  1867.
* Isoetes echinospora Boottii Engelm. in A. Gray, Man. Ed. 5, 676.  1867.
* Isoetes echinospora robusta Engelm. Trans. St. Louis Acad. 4: 380.  1882.
* Isoetes echinospora muricata Engelm. in A. Gray, Man. Ed. 5, 676.  1867.
* Submerged or in dry seasons emersed, leaves 10-70, tapering, soft, green, 3'-12' long, without peripheral bastbundles, bearing stomata only toward the tip; sporange orbicular or broadly elliptic, spotted, one-half to threefourths covered with the velum; macrospores 400-620 μ
* in diameter, covered with broad spinules which are often slightly confluent and incised at the tips; microspores 25-32 μ long, smooth.
* Labrador and Greenland to Alaska, south to New Jersey, Pennsylvania and California.

### 1.5

* 5.  Isoetes saccharàta  Engelm. Sugary Quillwort.   Fig. 122.
* Isoetes saccharata Engelm. in A. Gray, Man. Ed. 5, 676. 1867.
* Amphibious or uliginous with a flat depressed trunk. Leaves 10-30, green, pale at the base, spreading, 2'-5' long, quadrangular, bearing numerous stomata; sporange oblong, unspotted, with a narrow velum covering only one-fourth or one-third of its surface; peripheral bast-bundles wanting; ligule triangular, rather short; macrospores 420-510 μ in diameter, with very minute distinct or rarely confluent warts as if sprinkled with grains of sugar; microspores sparingly papillose, 22-30 μ long.
* In mud overflowed by the tides, eastern Maryland and District of Columbia.

### 1.6

* 6.  Isoetes ripària  Engelm. Riverbank Ouillwort.   Fig. 123.
* Isoetes riparia Engelm.; A. Br. Flora, 29: 178. 1846.
* Amphibious or uliginous, usually emersed when mature; leaves 10-30, green, rather rigid, 4'-8' long, quadrangular, bearing numerous stomata; peripheral bast-bundles wanting; ligule rather short, triangular; sporange mostly oblong, distinctly spotted with groups of brown cells, one-fourth to three-fourths covered with the velum; macrospores 450-756 μ in diameter, marked with distinct or anastomosing jagged crests or somewhat reticulate on the lower side; microspores 28-32 μ long, more or less tuberculate.
* Borders of the lower Delaware River.

### 1.7

* 7.  Isoetes foveolàta  A. A. Eaton. Pitted Quillwort.   Fig. 124.
* Isoetes foveolata A. A. Eaton; Dodge, Ferns and Fern Allies of New Eng. 38. 1896.
* Isoetes foveolata plenrospora A. A. Eaton, Rhodora 5: 280. 1903.
* Amphibious from a bilobed or rarely trilobed base.   Leaves 15-70, stout, 2'-6' long, pinkish even when dry, or rarely dark green; stomata scattered, found only near the tips; no peripheral bast-bundles; monoicous or becoming dioicous; velum covering ¼ or ⅓ of the sporange; ligule round-ovate; sporanges thickly sprinkled with dark cells which are often collected in groups; macrospores 380-560 μ, covered beneath with very thick-walled reticulations, the openings appearing like little pits; reticulations elongate on the upper surface of the spore; microspores dark brown. 22-35 μ long, densely reticulate and usually slightly papillose.
* In muddy banks, New Hampshire, Massachusetts and Connecticut.

### 1.8

* 8.  Isoetes Èatoni  Dodge. Eaton's Quillwort.   Fig. 125.
* Isoetes Eatoni Dodge, Ferns and Fern Allies of New Eng. 39. 1896.
* Amphibious from a large trunk ½'-1¼' in diameter.   Leaves of the submerged plant 30-200, varying in length up to 28', marked with an elevated ridge on the ventral side; leaves of the emersed plant shorter, 3-6; stomata abundant; peripheral bast-bundles irregular in occurrence or often wanting; velum covering ¼ of the sporange, polygamous; sporanges large, 0.4' by 0.15', pale spotted; macrospores small, 300-450 μ in diameter, marked with convolute labyrinthine ridges and cristate on the angles of the inner face; microspores 25-30 μ in diameter, minutely tuberculate.
* In mud flats, New Hampshire to New Jersey.

### 1.9

* 9.  Isoetes Dódgei  A. A. Eaton. Dodge's Quillwort.   Fig. 126.
* Isoetes Dodgei A. A. Eaton, Fern Bull. 6: 6. 1898.
* Isoetes canadensis A. A. Eaton, Proc. U. S. Nat. Mus. 23: 650. 1901.
* Plant amphibious from a bilobed trunk.   Leaves 10-75, 8′–18′ long when submersed, erect, or spirally ascending when scattered; emersed leaves 4′–6′ long, tortuous and often interlaced, with numerous stomata and usually
* 4 bast-bundles; velum narrow, covering 1/5 to 1/4 of the sporange; sporanges thickly sprinkled with light brown cells; macrospores more numerous on submersed plants, globose, 500-675 μ in diameter, sparsely covered with irregular crests which at maturity separate into irregular groups leaving bare spaces, serrate or spinulose at the top; microspores more numerous on emersed plants, 22-44 μ, ashy, papillose or wrinkled.
* Growing in mud flats, East Kingston, New Hampshire.

### 1.10

* 10.  Isoetes Engelmánni  A. Br. Engelmann's Quillwort.   Fig. 127.
* Isoetes Engelmanni A. Br. Flora, 29: 178. 1846.
* Isoetes Engelmanni fontana A. A. Eaton, Fern Bull. 13: 52. 1905.
* Isoetes Engelmanni gracilis Engelm. in A. Gray, Man. Ed. 5, 677. 1867.
* Isoetes Engelmanni valida Engelm. in A. Gray, Man. Ed. s, 677. 1867.

### 1.11

* 11.  Isoetes Gràvessi  A.A. Eaton. Grave's Quillwort.   Fig. 128.
* Isoetes Gravesii A. A. Eaton, Fernwort Papers 14.  1900.

### 1.12

* 12.  Isoetes melanópoda  J. Gay. Black-based Quillwort.   Fig. 129.
* I. melanopoda J. Gay, Bull. Soc. Bot. France, 11: 102.  1864.

### 1.13

* 13.  Isoetes bútleri  Engelm. Butler's Quillwort.   Fig. 130.
* Isoetes Butleri Engelm. Coult. Bot. Gaz. 3: 1.  1878.