module 10

• Types of plants


  • Non-vascular plants
  • Vascular plants without seeds
  • Vascular plants with seeds
• Non-vascular plants


  • First plants to evolve
  • Mostly small and lack vascular tissues
  • Lack true leaves, seeds, and flowers
  • Have hair-like rhizoids instead of roots
  • Niches in moist habitats but are not very efficient in absorbing water
  • Depends on moisture to reproduce and disperse
  • Reproduction is characterized by alternation of generations
• Divisions of Bryophyta (non-vascular plants)


  • Hepatophyta (Liverworts)
  • Anthocerophyta (Hornworts)
  • Bryophyta (Mosses)
• Hepatophyta (Liverworts)


  • Spore-producing non-vascular, thalloid or leafy plants
  • Small, generally inconspicuous plants that grow on moist soil, rocks, old stumps, and tree bark
  • Common in coniferous forests
  • Lack stomata
  • Flattened, lobed structure
  • Have thallus (hair-like rhizoids) on its underside
  • Doctrine of signatures: forms of liverworts was suggested to have medicinal value for the treatment of liver ailments
  • Leafy Liverworts have branching, leafy rather than lobed thallus, superficially resemble mosses, have prostrate, leafy 'shoots' and rhizoids, 'leaves' consists of a single undifferentiated cell, some reproduce asexually by forming gemmae
• Anthocerophyta (Hornworts)


  • Spore-producing, non-vascular thalloid plants
  • Small group of about 100 species
  • Live in disturbed habitats such as fallow fields and roadsides
  • Has single large chloroplast in each cell which resembles algae
  • Archegonia (female) and antheridia (male) are embedded in the thallus
  • After fertilization, the needle-like sporocyte projects out of the gametophyte of the thallus forming a spike, or 'horn'
  • Single gametophyte often produces multiple sporocytes
  • Meiosis occurs, during which spores from within each sporangium which then splits open form top to release the spores
  • Sporocytes of hornworts continue to grow from their bases for the remainder of the gametophyte's life

  
• Bryophyta (Mosses)


  • Usually lives in dense colonies or beds on moist soil, rocks, or tree bark
  • Has tiny hair-like rhizoids and an upright stem-like structure that bears leaf-like blades
  • Lack vascular tissues hence they do not have true roots, stems, or leaves
  • Some have water-conducting cells and sugar-conducting cells (not specialized or as effective as vascular plants)
  • Moss sporocyte is initially green and photosynthetic but turns golden brown at maturity
  • Important in forming soil, preventing soil erosion, retaining moisture, and used by some bird species as nesting material
• Vascular plants without seeds

  • Reproduce by forming spores rather than seeds
  • Have specialized vascular tissue (xylem and phloem)
  • Can grow larger than bryophytes
  • Have leaves that can perform photosynthesis
  • Microphyll - leaf found in lycophytes (contains one vascular strand)
  • Megaphyll - leaf found in all plants except lycophytes (contains multiple vascular strands)
• Divisions of seedless vascular plants

  • Pteridophyta (ferns)
  • Whisk ferns
  • Horsetails
• Pteridophyta (ferns)


  • Reproduce by spores produced in sporangia
  • Undergo alternation of generations between dominant sporophytes and a gametophyte (prothallus)
  • Terrestrial, although few have adapted to aquatic habitats
  • Found in tropical rain forests, temperate regions, swamps and marshes, moist woodlands and stream banks, fields, rocky crevices, on cliffs or mountains, or even deserts
  • Bracken (Pteridium aquilinum) is the most common fern species
• Whisk ferns


  • Reduced ferns
  • Live mainly in tropics and subtropics
  • Relatively simple in structure and lack true roots and leaves but have vascularized stems
  • Aerial stem resembles a whisk broom, hence the name
  • Rhizome with its attached rhizoids: absorbs water and dissolves minerals
  • Aerial stem are green and photosynthetic
  • Have dichotomous branching
• Horsetails


  • Few surviving horsetails, about 15 spp in the single genus Equisetum
  • Grow mostly in wet marshy habitats
  • Have true roots, stems (both rhizomes and erect aerial stems), and small leaves
  • Contains silica at jointed stem which gives it a gritty texture
  • Small leaves (interpreted as reduced megaphylls) are fused in whorls at each node
  • Have green stem (main organ for photosynthesis)
  • Also called "scouring rushes" and were used to scrub out pots and pans
  • Aerial stems are either vegetative (sterile) or reproductive (fertile)
  • Strobilus - terminal and cone-like found in the reproductive branch
  • Elaters - appendages in horsetail spores that uncoil as the spores dry out
  • Both sporophyte and gametophyte are photosynthetic and nutritionally independent upon maturity
  • Requires water as a medium for flagellated sperm cells to swim
• Divisions of seedless vascular plants

  • Lycopodia
  • Club mosses
  • Spike mosses
  • Quillworts
• Lycopodia


  • Some are heterosporous
  • Large treelike plants, like ancient horsetails were major contributors to our present day coal deposits
  • Characterized by leaves that are microphylls
• Club mosses


  • Small (<25cm, or 10 in tall), attractive plants common in temperate woodlands
  • Commonly known as "club mosses" and "ground pines"
  • Have true roots, rhizomes and erect or trailing aerial stems, and small, scale-like, single-veined leaves (microphylls)
  • Evergreen are often fashioned into Christmas wreaths
  • Life cycle is similar to that of ferns – both sporophyte and gametophyte are independent plants at maturity
  • Form symbiotic relationship with mycorrhizal fungi
  • Requires water as a medium in which flagellated sperms swim to the egg in the archegonium

  
• Spike mosses


  • Have long creeping rhizomes and typically branch dichotomously
  • Roots are produced at branching along the length of the stems
  • Overlapping, scalelike leaves, which are microphylls, have single unbranched vein; leaves are arranged in four vertical rows in many spp.
  • Ligule: inconspicuous outgrowth on the upper surface near the base of the leaf
  • Selaginella - living spike mosses; common in shady, moist tropics and subtropics, but some grow in temperate climates
  • S. lepidophylla -resurrected plant that are native to prairies and deserts of Texas and Mexico; curls up into a brown ball and becomes dormant when dry, but expands and becomes green and photosynthetic when moisture is available
• Quillworts (Isoetes)


  • Perennial aquatic or semiaquatic herbs that are widely distributed in temperate, freshwater habitats
  • Have a CORM with cylindrical, quill-like leaves (microphylls) grow in a clump from the base
  • Roots that arise from the corm divide dichotomously
  • Aerial stems are absent
  • Spore-bearing vascular plants
  • Megasporangia- produce few large megaspores; located at the bases of the outer leaves
  • Microsporangia – produce many smaller microspores that are at the bases of inner leaves
  • Requires water as a medium

  
• Homospory


  Production of one type of n spore that give rise to bisexual gametophytes
• Heterospory


  Production of two type of n spores, microspores, and megaspores
• Microspore


  The n spore in heterosporous plants that gives rise to a male gametophyte
• Megaspore


  The n spore in heterosporous plants that gives rise to female gametophyte
• Spike mosses, quillworts, and some ferns are heterosporous
• Types of vascular plants with seeds

  • Gymnosperms (non-flowering plants)
  • Angiosperms (flowering plants)

  
• Gymnosperms


  • Have needle-like or scale-like leaves and no flowers
  • Have woods that are softer than angiosperms and is used to make paper, furniture, and construction
• Rhizome growth


  1. Arise from the corm

  2. Divide dichotomously
• Aerial stems are absent
• Megasporangia


  • Produce few large megaspores
  • Located at the bases of the outer leaves
• Microsporangia


  • Produce many smaller microspores
  • Located at the bases of inner leaves
  • Requires water as a medium
• Gymnosperms (non-flowering plants)
• Gymnosperms


  Comes from the Greek words gymnos meaning "naked" and sperm which means "seed"
• Gymnosperms


  • Have needle-like or scale-like leaves and no flowers
  • Have woods that are softer than that of angiosperms and is used to make paper and lumber
  • Most are evergreens meaning they don't lose their leaves seasonally
  • Are also perennials (EVERGREEN), growing back every year with no need for replanting
  • Their reproductive system is located in the cones
• Female cones grow in the upper branches of the tree and male cones grown on the lower branches
• Phyla of Gymnosperms


  • CONIFEROPHYTA (Conifers)
  • CYCADOPHYTA (Cycads)
  • GINKGOPHYTA (Ginkgophytes)
  • GNETOPHYTA (Gnetophytes)
• CONIFEROPHYTA (Conifers)


  • Similar in production of secondary cambium and pattern of seed development with Cycadophyta and Ginkgophyta but are not closely related phylogenetically to each other
  • The dominant phylum of gymnosperms, with the most variety of species
  • Typically tall trees that usually bear scale-like or needle-like leaves
  • Water evaporation from leaves is reduced by their thin shape and the thick cuticle making the now slides easily off needle-shaped leaves, keeping the load light and decreasing breaking of branches
  • Adaptations to cold and dry weather explain the predominance of conifers at high altitudes and in cold climates
  • Coniferous trees are harvested for paper pulp and timber
  • Conifer woods are more primitive than the wood of angiosperms; it contains tracheids, but no vessel elements, and is, therefore, referred to as "soft wood"
  • Some species are deciduous (lose their leaves in fall)
• CYCADOPHYTA (Cycads)


  • Similar in production of secondary cambium and pattern of seed development with Coniferophyta and Ginkgophyta but are not closely related phylogenetically to each other
  • Thrive in mild climates
  • Often mistaken for palms because of the shape of their large, compound leaves
  • Bear large cones and may be pollinated by beetles rather than wind, which is unusual for a gymnosperm
  • Dominated the landscape during the age of dinosaurs in the Mesozoic, but only a hundred or so species persisted to modern times
  • Face possible extinction but several species are protected through international conventions
  • Often used as ornamental plants in gardens in the tropics and subtropics because of their attractive shape

  
• GINKGOPHYTA (Ginkgophytes)


  • Similar in production of secondary cambium and pattern of seed development with Cycadophyta and Coniferophyta but are not closely related phylogenetically to each other
  • Ginkgo biloba is the single surviving species of the gingkophytes group
  • Has fan-shaped leaves, unique among seed plants because they feature a dichotomous venation pattern, turn yellow in autumn and fall from the tree
  • Cultivated by Chinese Buddhist monks in monasteries for centuries, which ensured its preservation
  • Mostly planted in public spaces because it is unusually resistant to pollution
  • Male and female organs are produced on separate plants
• Gnetophytes


  • The closest relative to modern angiosperms
  • Have broad leaves like angiosperms
  • Are vines or small shrubs in tropical and subtropical zones
  • Like angiosperms, but unlike other gymnosperms, all gnetophytes possess vessel elements in their xylem
• Gnetophytes


  • Welwitschia
  • Ephedra - its small, scale-like leaves are the source of the compound ephedrine, which is used in medicine as a potent decongestant but use is restricted to prescription drugs because it has similar chemical structure and neurological effects to amphetamines
• Angiosperms (flowering plants)
• Angiosperms


  • Comes from the Greek words angeion meaning "redeptacle" and sperma meaning seed
  • Have flowers as their reproductive organ (stamen as the male part and carpel as the female part)
  • Have hard woods and are used a food, clothing, and medicine
  • Are seasonal, so they die during autumn
  • Range from a tiny herb, parasitic vines, to gigantic trees
• Groups of Angiosperms


  • BASAL ANGIOSPERMS
  • MONOCOTS
  • EUDICOTS