A SYNOPSIS OF THE PLANT KINGDOM 



tioned the wheat rust; the Hymenomycetes (Mush- 

 rooms, Toadstools, and Bracket Fungi), which are 

 saprophy tic or inhabit timber; and the Gasteromycetes 

 (Puff-balls), which are saprophy tic. The rusts exhibit 

 alternation of generations to a most remarkable degree, 

 the different generations often inhabiting different host 

 plants and possessing a wholly different appearance, as 

 well as a wholly different method of spore-formation. 

 The Hymenomycetes are saprophytic, except the genus 

 Exobasidium which inhabits the living foliage of various 

 plants, the genus Armillaria which infests living tree- 

 trunks, and many genera of the Polyporacese (Bracket 

 Fungi) which also attack the wood of living trees. The 

 last-mentioned fungi, including Armillaria, inhabit the 

 trunks and branches of forest trees, causing their death. 



CLASS XV. LICHENES (Lichens) 



Green, gray or highly colored plants of very diverse 

 habit and habitat, either thalloid, fruticose or crusta- 

 ceous, and growing on the soil, bark of trees, rocks, or 

 rarely on foliage: propagation by division of the thallus 

 or by the separation of special minute powdery parts 

 (soredia): spore-reproduction by ascospores borne in 

 perithecia or apothecia, rarely by basidiospores. The 

 lichen thallus is not a single organism, but is prob- 

 ably a symbiotic structure, comprised fundamentally 

 of fungus hyphse between which many unicellular green 

 algse are distributed, usually in a definite fashion. 

 The fungi belong to the Ascomycetes in the great 

 majority of cases, rarely to the Basidiomycetes. The 

 algae may belong to the Chlorophycese, in which case 

 they are unicellular, or to the Cyanophycea;, in which 

 case they are either unicellular or in chains. Because 

 the symbiotic structure behaves as a unit, it has been 

 decided to continue to treat the lichens as a class by 

 themselves, rather than to consider the algal and fungal 

 components Independently in their respective groups. 

 Except as soil-producers, lichens are of little economic 

 importance: Cetraria islandica furnishes Iceland moss; 

 Sticta pulnumaria was once used in medicine; Cladonia 

 rangiferina furnishes the main food of the reindeer in 

 Lapland, and, possibly, of other arctic animals; Roccella 

 tinctoria of Africa and the East Indies is the source of 

 the chemical indicator, litmus and of the dye orchil or 

 orseille. 



DIVISION II. BRYOPHYTA 



(Mosses and Liverworts) 



Small green plants of simple structure, either thalloid 

 or differentiated into stem and leaves: true roots 

 wanting: vascular tissue absent: alternation of gen- 

 erations well developed, the gamete-bearing generation 

 dominant: female gamete (egg) inclosed in a flask- 

 shaped multicellular archegonium : male gametes (sperm- 

 cells) inclosed within a multicellular antheridial wall: 

 fertilized egg producing the spore-bearing generation 

 (sporogonium) which consists of a parasitic or semi- 

 parasitic capsule usually borne upon a seta. 



The Bryophytes are divided into two great classes, 

 namely the Hepatic* (Liverworts) and the Musci 

 (Mosses). Each of these in turn is divided into several 

 orders, which, as usual, contain one or more families. 

 Mosses and liverworts are widely distributed over the 

 earth, the latter seeming to prefer limestone regions. 



The Hepatic* are characterized by a spore-bearing 

 generation consisting of a stalked or sessile simple cap- 

 sule, which contains spores and elongated sterile elaters, 

 and splits into teeth or valves at maturity. The 

 plant body (gamete-bearing generation) 'consists either 

 of a thalloid, algal-like, dichotomously branching, 

 ribbon-like structure, or of a slender axis bearing the 

 very thin leaves, one cell in thickness, and destitute 

 of a midrib. The leaves are usually arranged in two 

 lateral rows, with often a third row of small dissim- 



ilar leaves on the under side, so that the shoot is 

 strongly dorsi-ventral. The lateral leaves frequently 

 bear at the base a curious lobe that is infolded or 

 even flask-shaped, and probably aids in the conserva- 

 tion of water on the dry rocks and tree trunks which 

 many of these plants frequent. The under side of the 

 stem or thallus is usually provided with rhizoids that 

 take the place of roots. The thalloid liverworts are 

 inhabitants of damp or wet situations, some being 

 aquatic: in the North, they are found on damp soil, wet 

 rocks, or among damp moss. The majority of foliose 

 liverworts inhabit similar places, only comparatively 

 few genera and species being xerophytic. Filaments of 

 the alga, Nostoc, penetrate the cavities in the thallus 

 of Anthoceros and there form endophvtic colonies. Veg- 

 etative reproduction is accomplished by the branching 

 of the thallus, or by the production of special buds, 

 called gemma;, either on the edge of the loaf or thal- 

 lus, or in special cup-like receptacles borne on the sur- 

 face of the thallus. 



The Hepatica; are divided into four principal orders 

 as follows: Order I. Ricciales. Thalloid, floating or 

 amphibious: sexual organs sunken in the thallus: 

 capsule sessile, thin-walled, endophytic, irregularly 

 dehiscent. Order II. Marchantiales. Thalloid: arch- 

 egonia and antheridia usually borne on special branches 

 of the thallus: capsule often stalked, usually regularly 

 dehiscent. Marchantia was formerly used as a remedy 

 in diseases of the liver, hence the name liverwort. 

 Order III. Anthocerotales. Thalloid: one chloroplast 

 in each cell: sexual organs superficial: capsule very 

 slender, chlorophyll- and stomate-bearing, continuing 

 to elongate by basal growth. Order IV. Jungerman- 

 niales. . Thalloid or foliose: capsule usually splitting 

 to the base into four valves. 



The Musci (Mosses) differ from the Hepaticse mainly 

 in the more elaborate capsule, which in the young 

 state commonly contains chlorophyll, is provided with 

 stomates, and contains a central column of sterile 

 tissue (columella) encircled by the spore -bearing 

 chamber. The dehiscence of the capsule is apical and 

 transverse, and consists in the formation of a lid (oper- 

 culum) which falls off exposing the mouth of the an- 

 nular spore-chamber. This mouth is surrounded by a 

 single or double row of numerous hygroscopic teeth 

 (peristome), which, by their bending, regulate the 

 escape of snores in wet and dry weather. No elaters 

 are produced. The sporogonium of the moss is, there- 

 fore, not only a more independent structure from the 

 standpoint of nutrition than is that of most liverworts, 

 but is constructed along wholly different lines. On the 

 summit of the capsule is usually found a delicate, 

 diversely shaped, hood-like cap not organically con- 

 nected with it and easily detached, called the calyptra. 

 This is the enlarged upper portion of the archegonium, 

 which, after rupture, is borne aloft on the summit of 

 the growing sporogonium. The plant-body (gamete- 

 bearing generation) is never thalloid; and the leaves, 

 which are provided with a midrib, are frequently of 

 several cells in thickness. The germination of the spore 

 does not result at once in a moss plant, but produces 

 a creeping filamentous branched, algal-like growth 

 (protonema) on which at length are borne the buds 

 that give rise to the moss-stem proper. 



The Musci are subdivided as follows: Order I. 

 Sphagnales (Bog or Peat Mos.so.-0. Structure of stem 

 and leaf peculiar, consisting of dead, tracheid-like cells 

 without protoplasm and provided with pits or thicken- 

 ing bands, regularly interspersed among slender, living 

 cells containing protoplasm and chloroplastids. Under 

 ordinary conditions, the tracheid-like cells are filled 

 in part with air, and hence the plant has a grayish 

 hue. In the presence of rain or abundant soil-water, 

 the water is drawn into the cells by capillarity until 

 the still apparently dry plant contains a surprisingly 

 large quantity of water, which will flow out on squeezing 



