24 ISOETACEAE 



dorsally in the lower two thirds, ending in a slender white coiled hair 0.7-0.9 mm. long, 

 and with 8-12 minute cilia on each margin ; cones less than 5 mm. long, terminal on the 

 branches, the sporophylls similar to the ordinary leaves ; macrosporangia three-lobed, the 

 macrospores pale yellow, rugose-reticulate, 0.44 mm. in diameter ; microsporangia round- 

 reniform, the microspores bright yellow, smooth, 44 fi in diameter. 

 On rocks, mountains of southwestern North Carolina. 



5. Selaginella tortipila A. Br. Stems rooting only near the base ; branches] zigzag, 

 20-25 cm. long, primary ones elongated. Leaves about 6-ranked, loosely imbricated, 

 narrowly lanceolate, ciliate, scarcely channeled, tipped by a contorted or coiled hair : cones 

 4-5 mm. long, slightly 4-angled : bracts ovate-lanceolate, loosely spreading, dorsally 

 channeled. 



On rocky mountain tops, North Carolina and South Carolina. 



6. Selaginella rup6stris (L.) Spring. Stems and branches creeping, 5-10 cm. long, 

 zigzag, ascending at the tips ; primary branches short. Leaves closely imbricated, about 8- 

 ranked, 0.3-0.38 mm. wide, deeply channeled dorsally, with 6-9 cilia on each side, 

 tipped with a white spinulose awn about 1 mm. long : cones 1-1.5 cm. long, sharply 4- 

 angled : bracts similar to the leaves but broader and with shorter awns and more cilia. 



On dry rocks, Maine and Ontario to British Columbia, south to Georgia and Missouri. 



7. Selaginella acanthonota Underw. Stems and branches stout, rooting and ascend- 

 ing, softly plumose at the tips. Leaves of the stems in 8-10 regular series ; blades about 

 2 mm. long, gradually tapering into a roughened awn one-half to one-third their length, 

 with about 12 short irregular cilia on each side and similar cilia on either side of the dorsal 

 groove : cones fully 10 mm. long : bracts broadly triangular, ciliate like the leaf-blades. 



In sand, near the coast, North Carolina. Summer. 



Order 6. ISOETALES. 



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 ex- 

 cavated bases of the leaves, the sides more or less covered w r ith a fold of the 

 inner side of the leaf-blades (velum) ; those of the outer leaves usually contain 

 spherical, mostly sculptured macrospores, those of the inner contain minute 

 powdery oblong microspores ; the former germinate into prothallia bearing only 

 archegones, the latter into prothallia bearing usually only a single antherid. 



FAMILY 1. ISOETACEAE Horan. QUILLWORT FAMILY. 

 Characters of the order. 



1. ISOETES L. 



The only genus. Owing to their aquatic habitat and apparently local distribution, 

 these plants are popularly little known. Some species are called QUILLWORT. 



Velum incomplete or wanting. 



Amphibious : macrospores honeycombed-reticulated. 1. I. Engelmannii. 



Terrestrial : macrospores tuberculate. 



Polygamous : leaves 15-60, often blackish at the base. 2. I. melanopoda. 



Dioecious : leaves 8-15, bright green. 3. /. Butleri. 



Velum complete. 



Macrospores dark-colored : leaves 5-6 cm. long. 4. I. melanospora. 



Macrospores light-colored : leaves 40-60 cm. long. 5. L flaccida. 



1. Isoetes Engelmannii A. Br. Amphibious, usually partly immersed when mature. 

 Leaves 25-100, light green, quadrangular, tapering, 22-50 cm/ long, bearing abundant 

 stomata : peripheral bast-bundles present : sporanges oblong or linear-oblong, unspotted : 

 velum narrow : macrospores 400-520 fi in diameter, covered with honeycomb-like reticula- 

 tions : microspores 24-28 // long, mostly smooth. 



In ponds and ditches, rooting in mud, Maine to Delaware. Pennsylvania and Missouri. Repre- 

 sented in our range by /. Engelmannii Oeorgidna Engelm., which has fewer leaves and slightly larger 

 macrospores, and is known from Georgia; and by I. Engelmannii Carolinidna A. A. Eaton, which has 

 stouter leaves, a broader velum and larger brown densely muricate microspores; it occurs in the 

 mountains and middle country of North Carolina. 



2. Isoetes melanopoda J. Gay. Terrestrial, with a subglobose deeply 2-lobed trunk. 

 Leaves 15-60, slender, erect, bright green, with a blackish shining base, 12-15 cm. long, 

 3-angled, bearing stomata throughout, and well developed peripheral bast-bundles ; ligule 



