This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Subkingdom PTERIDOPHYTA. 1: 1-54.
Spores developing into flat or irregular prothallia, which bear the reproductive organs (antheridia and archegonia); flowers and seeds none.
i. Spores produced in sporanges, which are borne on the back of a leaf, in spikes or panicles, or in special conceptacles. Order 1. Filicales.
* Spores all of one sort and size (isosporous families).
t Vernation erect or inclined; sporanges in spikes, or panicles, opening by a transverse slit.
Fam. 1. Ophioglossaceae. 1: 1. ++ Vernation coiled; sporanges reticulated, usually provided with a ring (annulus). Sporanges opening vertically.
Sporanges panicled, with a rudimentary ring; marsh ferns. Fam. 2. Osmundaceae. 1: 7.
Sporanges sessile on a filiform receptacle; leaves filmy, translucent.
Fam. 3. Hymenophyllaceae. 1: 8.
Sporanges ovoid, in panicles, or spikes, provided with an apical ring. Fam. 4. Schisaeaceae. 1:9.
Sporanges opening transversely, provided with a vertical ring; borne in sori on the back or margin of a leaf. Fam. 5. Polypodiaceae. 1: 19.
** Spores of two sizes (microspores and macrospores).
Plants rooting in the mud; leaves 4-foliolate, or filiform. Fam. 6. Marsileaceae. 1: 36.
Plants floating; leaves entire, or 2-lobed. Fam. 7. Salviniaceae. 1: 37.
Order 2. Equisetales. One family.
Fam. 8. Equisetaceae. 1: 38. 3. Spores produced in sporanges, which are borne in the axils of scale-like or tubular leaves.
Order 3. Lycopodiales. Spores all of one sort and size. Fam. 9. Lycopodiaceae. 1: 42.
Spores of two sizes (microspores and macrospores).
Leaves scale-like, 4-many-ranked, on branching stems. Fam. 10. Selaginellaceae. 1: 48.
Leaves tubular, clustered on a corm-like trunk; aquatic or mud plants.
Fam. 11. Isoetaceae. 1: 50.
Subkingdom SPERMATOPHYTA. i: 55.
Microspores (pollen-grains) developing into a tubular prothallium (pollen-tube); macrospores (embryo-sac) developing a minute prothallium, and, together with it, remaining enclosed in the macrosporange (ovule) which ripens into a seed.
Class 1. GYMNOSPERMAE. Ovules not enclosed in an ovary. 1: 55-68.
Fruit a cone, with several or numerous scales, sometimes berry-like by their cohesion.
Fam. 1. Pinaceae. 1: 55. Fruit (in our genus) a fleshy integument nearly enclosing the seed. Fam. 2. Taxaceae. 1: 67.
Class 2. ANGIOSPERMAE. Ovules enclosed in an ovary. 1: 68.
Subclass I. Monocotyledones. i: 68
1. Carpels 1, or more, distinct (united, at least partially, in Family 6, Scheuchzeriaceae, where they are mostly united until maturity, and Family 8, Vallisneriaceae, aquatic herbs, with monoecious or dioecious flowers); parts of the flowers mosty unequal in number.
* Inflorescence various, not a true spadix.
+ Flowers not in the axils of dry chaffy scales (glumes); our species aquatic or marsh plants. % Endosperm mealy or fleshy; perianth of bristles or chaffy scales; flowers monoecious, spicate or capitate.
Order 1. Pandanales. Flowers spicate, the spikes terminal. Fam. 1. Typhaceae. 1: 68.
Flowers capitate, the heads axillary to leaf-like bracts. Fam. 2. Sparganiaceae. 1: 69.
++ Endosperm none, or very little; perianth corolla-like, or herbaceous, or none. Perianth wanting, or rudimentary. Order 2. Naiadales.
Carpels distinct; stigmas disk-like or cup-like. Fam. 3. Zannichelliaceae. 1: 74.
Carpels united; stigmas slender.
Flowers axillary; leaves spinose-dentate. Fam 4. Naiadaceae. 1: 89.
Flowers on a spadix; leaves grass-like. Fam. 5. Zosteraceae. 1: 90.
Perianth present, of 2 series of parts.
Carpels distinct. Order 3. Alismales.
Petals similar to the sepals; anthers mostly elongated. Fam. 6. Scheuchseriaceae. 1: 91.
Petals not similar to the sepals; anthers short. Fam. 7. Alismaceae. 1: 93.
Carpels united. Order 4. Hydrocharitales.
Ovary 1-celled with parietal placentae. Fam. 8. Vallisneriaceae. 1: 104.
Ovary 6-9-celled. Fam. 9. Hydrocharitaceae. 1:106. tt Flowers in the axils of dry chaffy scales (glumes), arranged in spikes or spikelets.
Order 5. Graminales (Glutniflorae).
Fruit a caryopsis (grain); stems (culms) mostly hollow in our species. Fam. 10. Gramineae. 1: 107.
Fruit an achene; stems (culms) solid. Fam. n. Cyperaceae. 1:295.
(Order 6, Palmales, including only the family Palmaceae, Palms, and Order 7, Cyclanthales, including only the family Cyclanthaceae, are not represented in our territory.)
** Inflorescence a fleshy spadix, with or without a spathe; or plants minute, floating "free, the flowers few or solitary on the margin or back of the thallus.
Order 8. Arales (Spathiflorae). Large herbs, with normal foliage and well-developed spadix. Fam. 12. Araceae. 1: 441.
Minute floating thalloid plants. Fam. 13. Lemnaceae. 1: 446.
2. Carpels united into a compound ovary; parts of the usually complete flowers mostly in 3's or 6 s.
* Seeds with endosperm.
t Flowers regular, or nearly so (corolla irregular in Commelina and Pontederia).
t Endosperm mealy; ovary superior.
Order 9. Xyridales (Farinosae).
a. Ovary 1-celled.
Aquatic moss-like leafy herbs; flowers solitary. Fam. 14. Mayacaceae. 1: 450.
Erect rush-like herbs; flowers in terminal scaly heads or spikes. Fam. 15. Xyridaceae. 1: 450.
Mud or aquatic herbs, the flowers subtended by spathes (Heteranthera in Pontederiaceae 1: 462).
b. Ovary 2-3-celled (except in some Pontederiaceae). Flowers very small, densely capitate, monoecious or dioecious. Fam. 16. Eriocaulaceae. 1: 453.