ISOETACEAE 25 



3-angled, awl-shaped : sporanges mostly oblong, spotted, with a narrow velum : polyga- 

 mous : macrospores 250-400 /z in diameter with low more or less confluent tubercles, often 

 united into worm-like wrinkles, or almost smooth : microspores 23-28 // long, spinulose. 



On moist prairies and in overflowed fields, Iowa to Illinois, Missouri and Texas. The Texan form 

 has larger leaves with pale bases. 



3. Isoetes Biitleri Engelm. Terrestrial, from a subglobose trunk. Leaves 8-15, 

 bright green, paler at base, triangular, 4.5-18 cm. long, bearing numerous stomata, and 

 with well developed peripheral bast-bundles, thick dissepiments and small air cavities : 

 sporanges usually oblong, spotted : velum very narrow or none : ligule small, triangular : 

 dioecious : macrospores 500-630 fj. in diameter, with distinct or confluent tubercles. 



On rocky hillsides, Missouri and Indian Territory. A variety, I. Butleri immaculdta Engelm., grow- 

 ing in the barrens about Nashville, Tennessee, has longer leaves, unspotted sporanges and spinulose 

 microspores. 



4. Isoetes melandspora Engelm. Stem flat, slightly 2-lobed. Leaves 5-10, dis- 

 tichous, slender, 5-6 cm. long, light green : sporanges orbicular or nearly obcordate, 1-2 

 mm. long, covered by the velum : ligule triangular, obtuse : macrospores * 350-450 /* long, 

 with distinct or confluent warts, dark-colored : microspores 28-31 fj. long. 



In shallow excavations in granite, slopes and summit of Stone Mountain and LittleJStone Moun- 

 tain, middle Georgia. 



5. Isoetes flaccida Shuttlw. Leaves 10-35, light green, 4-6 dm. long, submersed or 

 emersed. Sporanges oval, 4-6 mm. long, covered with numerous, or rarely few large flat- 

 tish tubercles, these distinct or confluent into labyrinthiform wrinkles. 



In lakes and ponds, western and peninsular Florida. A variety, I. flaccida rigida Engelm. from 

 Lake Flirt, is smaller, and has more slender and erect leaves. 



SUBKINGDOM SPERMATOPHYTA. SEED-BEARING PLANTS. 

 Plants producing seeds each of which contains an embryo consisting of 

 a short stem (radicle, caulicle or hypocotyl), one, two or several rudi- 

 mentary leaves (cotyledons) and a terminal bud (plumule). These parts 

 are sometimes partially un differentiated before germination. Microspor- 

 anges (anther-sacs) are borne on modified leaves (filaments) and contain 

 usually several or many microspores (pollen -grains). Macrosporanges 

 (ovules) are borne on the surface of a flat or inrolled modified leaf (car- 

 pel) and contain a macrospore (embryo-sac). A macrospore develops the 

 reduced female prothallium ; an egg-cell in an archegone of this prothal- 

 lium is fertilized by means of an elongating tube (pollen-tube), apart 

 of the male prothallium protruding from the pollen-grain (microspore) . 



Ovules and seeds borne on the face of a bract or a scale : stigmas wanting. Class 1. GYMNOSPERMAE. 

 Ovules and seeds in a closed cavity (ovary): stigmas present. Class 2. ANGIOSPERMAE. 



Class 1. GYMNOSPERMAE. 



Carpel or pistil represented by a scale or disk upon whose face are 

 borne the ovules (macrosporanges). Pollen-grains (microspores) divide 

 into two or several cells, one of which gives rise to the pollen-tube (male 

 prothallium) ; a sperm-cell or sperinatozoid developed at the end of a 

 pollen-tube directly fertilizes an egg-cell in the archegone of the embryo- 

 sac (female prothallium) in the ovule (macrosporange). 



Order 1. CYCADALES. 



Kelatively low palm-like plants. Stems scarred with the bases of fallen 

 leaves. Leaves aggregated in a terminal crown : blades pinnate. Flowers in 

 terminal or nearly terminal cones of often numerous approximate scales, or on 

 slightly modified leaves. Staminate cones with peltate or boat-shaped scales 

 supporting several pollen-sacs. Pistillate with two or more ovules on each flat 

 or shield-like scale. Seed drupe-like or nut-like. 



