KEY TO THE ORDERS: 
I. Plants without flowers or seeds, but producing spores each of which, on germination, develops into 
a flat or an irregulur prothallium. The prothallia bear the reproductive organs (antheridia and 
archegonia). As a result of the fertilization of an egg in the archegonium by a sperm produced in 
the antheridium a fern or an allied plant is developed. 
PAGE. 
I. PTERIDOPHYTA. 1 
Leaves with broad entire or dissected blades. (Fern-like plants. ) 
Spores of one kind, minute. 
Vernation straight or inclined: prothallium subterranean, yellowish. ; 
Order OPHIOGLOSSALES. 1 
Vernation circinate: prothallium terrestrial or epiphytic, green. Order FILICALES. 3 
Spores of two kinds, minute microspores and larger macrospores, borne in sporocarps. 
Order SALVINIALES. 19 
Leaves scale-like or awl-like. (Moss-like or rush-like plants.) 
Sporangia in an apical cone, borne under peltate scales: stems hollow, rush-like. 
Order EQUISETALES. 20 
Sporangia in the axils of small or leaf-like bracts: stems solid. 
Leaves narrow or scale-like, flat, borne on erect or creeping stems: terrestrial plants. 
Order LYCOPODIALES. 21 
Leaves awl-like, often much elongated, borne on a short corm-like caudex : aquatic plants. 
Order ISOETALES. 24 
II. Plants with flowers which produee seeds. Mierospores (pollen-grains) borne in microsporangia 
(anther-sacs) develop each into a tubular prothallium; a macrospore (embryo-sac) develops a 
minute prothallium, and together with the maerosporangium (ovule) in which it is contained, 
ripens into a seed. 
II. SPERMATOPHYTA. 25 
Ovules and seeds borne on the face of a bract or a scale: stigmas wanting. Class 1. GYMNOSPERMAE. 
Ovules and seeds in a elosed cavity (ovary): stigmas present. Class 2. ANGIOSPERMAE. 
1. Gymnospermae. 
Plants growing by a single terminal bud, with pinnate leaves circinate in vernation: embryo pro- 
longed into a spiral. $ : Order CYCADALES. 25 
Plants growing by lateral as well as by terminal buds, with scale-like, flat or needle-like leaves 
not circinate: embryo not prolonged into a spiral. Order PINALES. 26 
2. Angiospermae. 
Cotyledon 1: stem endogenous. Subclass 1. MONOCOTYLEDONES. 
Cotyledons normally 2: stem exogenous (with rare exceptions). Subclass 2. DICOTYLEDONES. 
1. MONOCOTYLEDONES. 
Perianth rudimentary or degenerate, the members often bristles or mere scales, not corolla-like, 
or wanting. 
Flowers noe in the axils of dry or chaffy bracts (scales or glumes). 
Perianth of bristles or chaffy scales. _ Order PANDANALES. 
Perianth fieshy or herbaceous, or wanting. 
Fruit baccate: endosperm present. | Order ARALES. 
Fruit drupaceous: endosperm wanting. : Order NAIADALES. 
Flowers in the axils of dry or chaffy, usually imbricated, bracts (scales or Sum 
rder POALES. 48 
gd g 
. Perianth of 2 distinet series, the inner series usually corolloid. 
erem m E ed rg Order ALISMALES. 40 
ynoecium of united carpels. 
r Endosperm mealy. P Order XYRIDALES. 231 
Endosperm fleshy, horny or cartilaginous. 
A. Ovary, and fruit, superior. ee i : 
a. Herbs, or rarely shrubs or trees, with simple leaves: ovules 2-many in each cavity of 
the ovary, or solitary only in the case of a few herbs. 
Inflorescence not a fleshy spadix. Order LILIALES. 247 
Inflorescence a fleshy spadix subtended by a spathe. Order ARALES. 225 
! Prepared with the assistance of Dr. P. A. Rydberg. 
vii 
