Quiz 12C Plant Classification One of the traits used in classifying plants is the presence or absence of vascular tissue. Xylem and phloem are the most familiar, but there are others.
Vascular plants: plants that have vascular tissue. Nonvascular plants: plants that do not have vascular tissue. Do you think that plants without vascular tissues are tall or short? Why?
Another important trait used to classify plants is whether they produce seeds. Nonvascular plants – seedless and reproduce by producing gametes in one stage of their life cycle and spores. Vascular plants – some reproduce by gametes and spores & others by gametes and seeds.
Non-vascular plants Phylum Bryophyta moss liverwort hornwort
Non-vascular plants These plants are called bryophytes. Phylum Bryophyta (means “mosslike plant”)
Non-vascular plants • Water and other materials are transported by diffusion. • Fairly short.
Non-vascular plants • Sometimes have parts that look like roots, stems, or leaves, but there is no vascular tissue so they don’t have roots, stems, or leaves. • Live near water or shady places.
Just because a plant has the word “moss” in its name, doesn’t make it moss. Examples … • Irish moss (algae) • Reindeer moss (lichen – fungus & algae • Spanish moss (flowering plant)
Parts of a moss plant leafy shoot- a slender stalk with leaflike structures; each of the tiny leaflike structures on moss is 1 cell layer thick rhizoids- tiny hairless threads which grows into the soil to absorb water and minerals; not roots- lack conditioning tissue
Parts of a moss plant Leafy Shoot Rhizoids
Life Cycle of Moss Alternation of Generations • Sporophyte Generation: produces spores (asexual) • Gametophyte Generation: produces gametes (sexual)
Life Cycle of Moss Gametophyte Generation • The top of the male gametophyte bears the antheridia which produces sperm • The top of the female gametophyte has one or more archegonia which contains the ova • Sperm swim from the antheridia to the archegonia and fertilizes an ovum (zygote)
Life Cycle of Moss Sporophyte Generation • Zygote grows into a stalk with a capsule which produces spores • When mature the cap comes off and spores disperse • Spore grows when environmental conditions are right • First grows into a cellular filament called a protonema • Protonema then forms the leafy shoots and rhizoids
Life Cycle of Moss Protonema
Liverworts “Liver Plant” Marchantia – a common liverwort with a y-shaped thallus Have splash platforms which look like little umbrellas
Benefits of Mosses • Help to replenish the soil • Help to prevent soil erosion • Peat moss or Sphagnum is used by gardeners to pack plants for shipment and in Iceland and other northern regions it is used as fuel • Has been used for surgical dressing
Phylum Pterophyta Ferns Vascular Plants Without Seeds
Ferns: nonflowering vascular plants • Spore-bearing leaves • Horizontal undergound stems • 1-2 feet tall • Tropical ferns may grow as tall as 60 ft. with fronds 12-14 ft. • Some are epiphytes
Parts of a fern: • Fronds – leaves • Rhizome – a creeping or underground stem, which produce roots • Sori – groups of spore-bearing sporangia (means “a heap”)
Fern Sori Sori may be round, kidney-shaped, oblong, linear, curved, or star-shaped.
Sporophyte Generation of Ferns A new fern’s life cycle typically begins in July with the appearance of sori on the undersurface or along the margins of a frond.
Sporophyte Generation • Sori appear on the underside of a frond. • Sori first open and discharge millions of spores.
Gametophyte Generation Spore develops into a tiny green, heart-shaped structure called a prothallus. Seldom seen, only 1 cell layer in thickness.
Gametophyte Generation The underside of the prothallus develops archegonia and antheridia Antheridia near the point (sperm) Archegonia at notched end (ova)
Gametophyte Generation Sperm are released from the antheridia and swim to the ovum at the bottom of the archegonia.
Sporophyte Generation Zygote matures and sends the first leaf up and the first root down. The first leaf is often a fan-shaped blade. The second leaf is usually a fiddlehead, a coiled young leaf. Some fiddleheads are edible and used in salads.
Fern Alternation of Generation Facts Ferns usually require 3-7 years to reach reproductive maturity. Fern plants (sporophytes) live for several years and produce new fronds each year Dominant generation:Sporophyte
Fern Alternation of Generation Facts Protellia (gametophytes) only live 3-7 weeks, in which time they produce the archegonia and antheridia. Dominant generation: Sporophyte
Other seedless vascular plants: club moss, whiskfern & horsetail club moss whiskfern horsetail
club moss club mosses: (also called "ground pine" because they grow along the ground in temperate regions)
horsetail • all but one group have become extinct • the epidermis contains a glasslike substance (silica) which feels very rough to the touch • called "scouring rushes" - used for scouring pots and pans before scouring powder and pads were known.
Vascular Plants with Seeds These plants do not require water for sexual reproduction. They reproduce by seeds rather than spores. Seeds are multicellular and contain a young plant called an embryo.
Vascular Plants with Seeds Two main groups of seed plants: Gymnosperm Angiosperms
gymnosperms • the seed plants that do not first produce a flower before the seed • means "naked seed" - produce seeds not covered by the walls of an ovary • do not form flowers or fruits • produce cones or cone-like structures
angiosperms • The Flowering Plants – means “covered seed” • All have seed enclosed in a fruit • All have flowers (not all are colorful blossoms - corn tassels and catkins of oak trees)