ISOETACEAE 25 
3-angled, awl-shaped : sporanges mostly oblong, spotted, with a narrow velum: polyga- 
mous: macrospores 250—400 u in diameter with low more or less confluent tubercles, often 
united into worm-like wrinkles, or almost smooth : microspores 23-28 u long, spinulose. 
On moist prairies and in overflowed fields, Iowa to Illinois, Missouri and Texas.—The Texan form 
bas larger leaves with pale bases. 
3. Isoetes Bütleri Engelm. Terrestrial, from a subglobose trunk. Leaves 8-15, 
bright green, paler at base, triangular, 4.5-18 em. 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 x 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 u long, 
with distinct or confluent warts, dark-colored : microspores 28-31 « long. 
In shallow excavations in granite, slopes and summit of Stone Mountain and Little Stone 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 undifferentiated 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), a part 
of the male prothallium protruding from the pollen-grain (microspore). 
Ovules and seeds borne on the face of a bract or ascale: 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 spermatozoid 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. 
Relatively 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, 
