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Chapter 21; Nonvascular Plants: Mosses, Liverworts, and Hornworts -…
Chapter 21; Nonvascular Plants: Mosses, Liverworts, and Hornworts
characteristics of nonvascular plants
embryophytes that do not have vascular tissue
contain multicelluar sporangia and gametangia
reproductive cells always surrounded by layers of sterile cells
bodies composed of true parenchyma
leafy stems that look like small versions of flowering plants
division bryophyta; mosses
morphology
gametophores - leafy stems of moss
moss gametophores grow from apical meristems that contain a prominent apical cell
water transport
Hydroids - cells in the innermost cortex that conduct water and dissolved minerals
leptoids - cells in mosses that resemble sieve cells and are elongate with relatively prominent interconnections with adjacent cells
most mosses lack hydroids and leptoid
rhizoids - small multicellular structures at the base of the stem that penetrate the the surface if the substrate
reproduction
antheridia - microgamtangia where sperm is produced
archegonia - megagametangia where eggs are produced
development
protonema - branched systems of long, slender chlorophyllous cells
sporophyte generation
foot - small bulbous tissue at the bottom of the archegonium
capsule - simple apical sporangium consisting of an outer layer of sterile cells and an inner column of sterile cells
seta - narrow stalk between the foot and the capsule
operculum - apex of the sporangium which separates from the rest of the sporangium as cells are torn apart
peristome teeth - complex teeth resulting from cell breakage. respond to humidity to open when air is dry and bend inward when air is humid
division hepatophyta: liverworts
small plants that like mosses have an alternation of heteromorphic generations
gametophore generation
leafy liverworts - gametophore resemble that of mosses
thallose liverworts - gametophores are not leafy at all
thallus - body of liverwort gametophore
air pores - openings in aerenchyma cell
antheridiophore - umbrella like outgrowth of of male gametophore
archegoniophore - stalked with apex made of radiating fingers
sporophyte generation
elaters - single, elongated cells with spring like walls
when the sporangium opens, the elaters uncoil, pushing the spores out
division anthocerotyphyta: hornworts
hornworts - small group of thalloid plants that grow on moist soil
