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Chapter 21: nonvascular plants: mosses, liverworts, and hornworts - Coggle…
Chapter 21: nonvascular plants: mosses, liverworts, and hornworts
Concepts
Nonvascular plants
- often called brophytes and Don't have vascular tissues or seeds
Ex: mosses, liverworts, hornworts
vascular cryptogams
- Have vascular tissue but not seeds
Ex: clubmosses, scouring rushes, ferns
Spermatophytes
- Have both vascular tissue and seeds
Ex: cycads, conifers, angiosperms
Means of coping with dry periods
Not coping
- The least expensive-The organism dies.
Desiccation tolerance
- Many mosses, liverworts, and lichens and some terrestrial algae have the ability to survive even when their body loses large amount of water. The plants do not permit rapid metabolism and grow slowly
Formation of spores
- Most of the body dies during times of stress while if you cells are made stress tolerant to live.
Desiccation avoidance
- The organism avoids dry conditions by either retaining water within itself or tapping a safe relatively permanent source of water. This method allows some metabolism on all the time and growth and reproduction can be somewhat independent of dry cycles.
Production of pollen and seeds eliminates the need for environmental water for reproduction.
Characteristics and Classification of nonvascular plants
Non-vascular plants are technically embryophytes that do not have fescue or tissue. Bing embryophytes, they have multicellular sporangia and gametangia: Reproductive cells are always surrounded by one or several layers of sterile cells.
Almost exclusively terrestrial and have a cuticle over much of their bodies and Minnie have stomata
Nonvascular plants to have a life cycle with an alternation of heteromorphic generations
Vascular plants can never grow to be really large, but being small and simple provides great slept advantage in certain habitats. They thrive in microhabitat such as stone walls, fences, and bare rocks.
It is not known how closely related mosses, liverworts, and hornworts are. They have many features in common but also different in significant respects.
Division Bryophyta:
Mosses
Mosses are ubiquitous, Occurring in all parts of the world in almost every environment.
Morphology
The Weepies stems, technically known as gametophores, Of Minnie mouse plants grow close together, tightly appressed informing dense mounds. In other species particularly those of cool areas the plants or more open and loose.
Moss gametophores Grow from an apical meristem that contains a prominent apical cell.
Systems are always slender and have a little fat tissue differentiation. The surface layer is at most only slightly different from the underlying layers and is not called epidermidis. The stem tissues (all called cortex) maybe in uniform parts, or the other cells may be slightly narrower with thicker walls.
Water Transport
Hydroids
- Cells in the inner most cortex that conduct water and dissolved minerals. They are in long gated cells that lose their cytoplasm when fully mature. Their end walls or partially digested but they are not removed entirely.
Leptoids
- Elongated cells with relatively permanent interconnections with adjacent cells that lack nuclei at maturity. Often seen species that have hydroids as well
Rhizoids
- Small, multicellular Trichome like structures that penetrate the surface of the substrate. They anchor the stem and do not absorb water or minerals
Development
Protonema
- Branched system of cells similar to slender chlorophyllous cell. Nodules of small cytoplasmic cells form on the Protonema, organize an apical cell, and then grow up right as a stem with leaves
Reproduction
All mosses are oogamous, meaning Every species has small by flagellate sperm cells in large non-motile egg cells
Antheridia- Sperm are produced. Consists of a short stock. An inner mass of cells that differentiate into sperm cells inside a layer of sterile cells
Eggs occur in megagametangia called archegonia.
The operculum is a cap like lid separating the sporangium. The sporangium is covered Are you layer of cells derived from the neck of the archegonium, called the calyptra.
Peristome Teeth respond to humidity by bending outward and opening the sporangium..
Division Hepatophyta: Liverworts
Liverworts are small plants that have an alternation Of heteromorphic generations.
Two Basic groups of liverworts: Leafy and thallose
In both, the gametophyte face is initiated when sports germinate and establish a small temporary protonematal phase
Thallose Liverworts show less resemblance to mosses. They are not leafy at all but rather flat and bilaterally symmetrical. The body is sometimes referred to as a thallus, A body without roots, stems, and leaves. The cells are loosely arranged as an aerenchyma with large air chambers that open to the exterior by means of large airports
Males Produce an umbrella Like outgrowth called an
antheridiophore
Within the sporangium some cells do not undergo meiosis but rather differentiate into elators- Single, elongate cells with spring shaped walls. When the sporangium opens, the elaters uncoil pushing the spores ou
All are homosporous
Division Anthocerotophyta:
Hornworts
Hornworts are a small inconspicuous thalloid plants That grow on moist soil, hidden by grasses and other herbs. They rarely inhabit tree trunks or bare rocks.
Hornworts superficially resemble the thalloid liverworts, the gametophores Of many species being ribbon shaped and thin without the distinct stem or leaves.
Gametangium Develop Ment and hornworts is distinctive. Unlike all other embryophytes the antheridial Initials are not surface cells on the hornwort gametophyte. A Special mucilages chamber forms near the upper surface; then cells lining the chamber grow into it and become antheridia.
