GENERAL KEY TO THE ORDERS AND FAMILIES 



Subkingdom PTERIDOPHYTA. i: 1-54. 



SPORES DEVELOPING INTO FLAT OR IRREGULAR PROTHALLIA, WHICH BEAR THE REPRODUCTIVE ORGANS 

 (ANTHERIDIA AND ARCHEGONIA) ; FLOWERS AND SEEDS NONE. 



1. Spores produced in sporanges, which are borne on the back of a leaf, in spikes or panicles, or 



in special conceptacles. Order i. 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. i. Ophioglossaceae. l:i. 



tt Vernation coiled; sporanges reticulated, usually provided with a ring (annulus). 

 Sporanges opening vertically. 



Sporanges panicled, with a rudimentary ring; marsh ferns. Fam. 2. Osmundaceae. i : 7. 



Sporanges sessile on a filiform receptacle ; leaves filmy, translucent. 



Fam. 3. Hymenophyllaceae. i : 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. Polypodiaceac. 1:19. 



** Spores of two sizes (microspores and macrospores). 



Plants rooting in the mud ; leaves 4-foliolate, or filiform. Fam. 6. Marsileaceae. i : 36. 



Plants floating ; leaves entire, or 2-lobed. Fam. 7. Salviniaceae. I : 37. 



2. Spores produced in sporanges, which are clustered underneath the scales of a terminal cone- 



like spike; stems jointed, rush-like. 



Order 2. EQUISETALES. 

 One family. 



Fam. 8. Equisetaceae. i : 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. i : 42. 



Spores of two sizes (microspores and macrospores). 



Leaves scale-like, 4-many-ranked, on branching stems. Fam. 10. Selaginellaceae. i : 48. 



Leaves tubular, clustered on a corm-like trunk ; aquatic or mud plants. 



Fam. ii. Isoetaceae. i : 50. 



Subkingdom SPERMATOPHYTA. i: 55. 



MICROSPORES (POLLEN-GRAINS) DEVELOPING INTO A TUBULAR PROTHALLIUM (POLLEN-TUBE) ; MACRO- 

 SPORES (EMBRYO-SAC) DEVELOPING A MINUTE PROTHALLIUM, AND, TOGETHER WITH IT, 

 REMAINING ENCLOSED IN THE MACROSPORANGE (OVULE) WHICH RIPENS INTO A SEED. 



Class i. GYMNOSPERMAE. Ovules not enclosed in an ovary. i : 55-68. 



Fruit a cone, with several or numerous scales, sometimes berry-like by their cohesion. 



Fam. i. Pinaceae. 1:55. 

 Fruit (in our genus) a fleshy integument nearly enclosing the seed. Fam. 2. Taxaceae. i : 67. 



Class 2. ANGIOSPERMAE. Ovules enclosed in an ovary. i : 68. 



Subclass i. MONOCOTYLEDONES. i : 68 



EMBRYO WITH i COTYLEDON ; STEM WITH NO DISTINCTION INTO PITH, WOOD AND BARK; LEAVES MOSTLY 



PARALLEL-VEINED. 



i. Carpels i, 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. 



t Flowers not in the axils of dry chaffy scales (glumes) ; our species aquatic or marsh plants, 

 t Endosperm mealy or fleshy ; perianth of bristles or chaffy scales ; flowers monoecious, spicate or 



capitate. 



Order i. PANDANALES. 



Flowers spicate, the spikes terminal. Fam. i. Typhaceae. i : 68. 



Flowers capitate, the heads axillary to leaf-like bracts. Fam. 2. Sparganiaceae. i : 69. . 



t J 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. i : 74. 



Carpels united ; stigmas slender. 



Flowers axillary ; leaves spinose-dentate. Fam 4. Naiadaceae. i : 89. 



Flowers on a spadix ; leaves grass-like. Fam. 5. Zosteraceae. i : 90. 



Perianth present, of 2 series of parts. 



xxii 



