10 



A SVXDl'SIS OF THE PLANT KINGDOIM 



At inatvirity, a pelatinoiis mass escapes from tlie 

 svx>n.iearp, anii on tliis mass the sori arc borne in 

 stMiiewhat characteristic fashion in ihtTcrcnt species. 

 The leaflets of the clover-like leaves of Marsilea, in 

 eiiierswl forms, show sFwp movement, ;us do those of 

 clover. These leaflet^s tioal upon the water to the vary- 

 ing depths of which the petioles accommodate them- 

 selves; hut the plant ma.\- prow emersinl on mud, in 

 which e;ise the i>etioles are erect like clover. The leaves 

 of Pilularia are filiform, jiointed, and destitute of blade. 



In .\uslraUa. the sporocarps of Mnnsilcn \arilii and 

 M. Druninioiiilii, which contain much starch and other 

 nutritious material, are used by the natives for food. 

 Thev are prountl into a powder, mixed with water and 

 baked. Fish and marsilea "fruits" form almost the 

 sole food of some tribes. 



One species, Marcilrn quadrifolia, is in cultivation 

 in .\merica for acjuatic gardens. 



11. Salviniacese (from the genus Salmnin in honor of 

 A. M. ,'>alvini. Italian scientist). Salvini.\ Family. 

 Fig. 3. Small, floating aquatic plants, resembling large 

 Lemnas (Salvinia) or foliaceous liverworts (AzoUa) : 

 stem riiiuced or wanting: leaves few, orbicular or oval 

 (Salvinia); or mutierous, minute and imbricated 

 (AzoUa): sporangia and spores of two sorts as in Mar- 

 silea, but borne on basal columns in the single cavity 

 of the SDorocarp: at first both sorts of sporangia are 

 present but only one kind matures so that the sporo- 

 carp becomes entirely "male" or entirely "female;" 

 prothallium partly endosporous, only a portion of either 

 the male or female prothallium emerging from the 

 spore wall. 



The family hius 2 genera and about 15 species, of 

 which 11 belong to Salvinia; generally distributed but 

 principally tropical. Each genus is represented in the 

 eastern Unitetl States by one native species. The 

 family is related to the Marsileacea?, but the habit, the 

 structure of the sporocarps, and the separation of 

 macrosporangia and microsporangia in different sporo- 

 carps are distinctive. 



The "roots" of Salvinia represent a modified leaf. 

 Each leaf of AzoUa is two-lobed, one lobe floating, 

 the other submerged. .\ small cavity inclosed by the 

 upper lobe is always inhabited by a nostoc-like alga, 

 between which and the Azolla there is indication of a 

 symbiotic relationship. Azolla possesses true roots. 



The family is of almost no economic importance. 



One species of Salvinia and two species of AzoUa 

 are occasionally grown in water-gardens. 



CLASS II. EQUISETIN.^ 

 Order 5. Eqdisetales 



12. Eouisetaceae (from the genus Equisetum, meaning 

 hoTne-bristk). Horse-tail Family. Fig. 1. Plants of 

 striking appearance, often with rhizomes and with a 

 straight, aerial, striated axis bearing whorLs of connate, 

 scale-like leaves at the nodes; from the nodes also fre- 

 quently ari.w slender branches of different structure 

 which bear different but still scale-like leaves; the stem 

 is hollow, and besides the central canal often contains 

 numerous additional large canals imbedded in the 

 outer tissue; sports of one kind (not microspores and 

 macrosporesi; sporangia 5-9, borne on the under 

 surface of peltate, polygonal scales which form a 

 terminal cone; dehi.scence longitudinal; spores green, 

 provided with several hygroscopic "elaters" which aid 

 in dis.-iemination; prothallia green, unisexual, the female 

 largest, branched. 



A single genus and about 24 species are known, of 

 which one section is tropical, the other of temperate 

 distribution. Ten species are native in the eastern 

 United Statf*. The family is very distinct and shows 

 no definite relationship to any existing plants. The 

 habit, the undilTcrcntiated spores, the peltate sporo- 

 phylls, and the liiacious emergent prothallia are dis- 



tinctive. The arrangement of the canals and also 

 of tlu' stomates along the stem are important in the 

 <listinction of species. 



The stems of E. hiemtile, rich in silica, were formerly 

 much used for scouring and for polishing woods, and 

 are still used to some extent. PJ. arvense and E. si/lvali- 

 ciim have been used for polishing tin vessels, hence the 

 name "tinweed." Several species have been used in 

 medicine, as diuretics. E. gigntiteum is emplo.yed as an 

 astringent. E. arvense and E. palustre are bad weeds 

 in parts of Europe. 



Se\'eral species have been advertised by American 

 dealers in native plants. 



CLASS III. LYCOPODIN^ 

 Order 6. Lycopodiales 



13. Lycopodiaceae (from the genus Lycopodium, wolf- 

 foot, from a fancied resemblance). Club-Moss Family. 

 Hg. 1. Branched plants of moderate size, stems often 

 erect when short, usually prostrate, pendent, or creep- 

 ing; leaves very numerous, small, subulate or oblong, 

 mo.ss-like, often imbricated; rarely the leaves all basal 

 (Phylloglossum); sporophylls either similar to the 

 leaves, or much modified and forming terminal "cones;" 

 sporangia and spores of one sort (not macrospores and 

 microspores), the former reniform, borne at the base 

 of a leaf on the upper side; dehiscence longitudinal; 

 prothallia more or less cylindrical or amorphous, in some 

 species green, in others colorless, saprophytic, sub- 

 terranean or subcortical. 



The club-moss family contains 2 genera and about 

 100 species, aU but one of which belong to Lycopodium, 

 distributed in aU parts of the world except the very 

 dry regions. The majority of the epiphytic species 

 are tropical, but several terrestrial species extend to 

 the arctic circle. Twelve of the species are native in the 

 eastern United States. The family is not closely related 

 to any other. The habit, the undifferentiated spores, 

 and the prothaUium are distinctive. 



The branching of Lycopodium is of two types, the 

 dichotomous, and the monopodial (a central axis from 

 which lateral branches arise). On these types sub- 

 genera are based. 



The spores of Lycopodium (principaUy of L. clava- 

 tu7)i), which are produced in great quantities, are used 

 by apothecaries for coating pills, and by metal-workers. 

 These spores are highly inflammable and were formerly- 

 used in theaters to produce flashlights. L. Selago is 

 emetic, drastic, vermifugal, and emmenagogue. L. 

 myrsinUis and L. calharlicum are purgative. Several 

 other species have been used locally for various com- 

 plaints. The creeping stems of L. clavatum and L. 

 complanatum are often used for Christmas and church 

 decorations. 



S(!veral species of Lycopodium (Club-moss, Grouiid 

 Pine, Creeping Pine) are gathered or protected in 

 America for decorative purposes or for the spores. 



Order 7. Selaginellales 



14. Selaginellaceae (from the genus Selaginella, 

 diminutive of Selago, ancient name of Lycopodium). 

 SELAfiiNELLA Family. Fig 1. Moss-like or lycopodium- 

 like plants, often of moderate size, usuaUy profusely 

 and dichotomously branched, more rarely monopodial; 

 creeping, pendent or erect, sometimes climbing and 

 several meters long, or minute and 1-3 cm. long; 

 leaves moss-like, very small, usuaUy densely placed, 

 often imbricated, often of two sizes (the branches 

 therefore strongly dorsiventral) ; ligule present, borne 

 at the base of the leaf on the upper side; roots borne on 

 "rhizophores" which are probably modified branches: 

 siiores of two sorts (microspores and macrospores) in 

 separate sporangia, borne in the leaf axils; sporophylls 

 fre(iuently inoilified, forming a cone or spike; prothallia 



