Bryophytes Flashcards
Characteristics plants share with green algae
- primary photosynthetic pigments (chlorophyll a, b , carotenoids)
- primary energy storage compound (starch)
- cell walls cellulose
- form phragmoplasts and cell plates during division
phragmoplasts
complex of microtubules and endoplasmic reticulum.
- acts as a framework for cell plate assembly and subsequent formation of the future cell wall separating the two daughter cells.
pectin
pectin helps keep the walls of adjacent cells joined together.
How do plants differ from algae
moss have:
- epidermal cells have a waxy cuticle
- multicelled sporangia surround developing spores
- multicelled gametangia surround developing gametes
- embryos are surrounded by protective cells
Specific bryophye characteristics:
- no vascular tissue… nonvascular plants lack lignified water-conducting tissues
- gametophyte generation is dominant
- fewer specialized tissue
- motile, multiflagellated sperm
three classes of bryophyta
- class sphagnopsida
- class bryopsida
- class andreaopsida
class sphagnopsida
peat mosses
class bryopsida
true mosses
class andreaopsida
rock mosses
phylum bryophyta structure of leaves
- gametophyte thallus is threadlike with narrow leaflike projections attached to stem
- no veins
- thin
- no petiole (leafstalk)
- no mesophyll or stomata
phylum bryophyta axis structure
- no conductive tissue (not a stem)
- may have hydroids (sponge cells that soak up water)
phylum bryophyta rhizoids
- threadlike, anchor base
- help absorb but not a root
Phylum bryophyta gametangia
- form by mitosis near tips of gametophyte or on special stalks
gametangia
specialized organ or cell in which gametes are formed
antheridia
male, looks like hot dog on stick, produces sperm
archegonia
female, produces ovum
paraphyses
grows around the anteridium/archegonium
moss fertilization
- antheridium swells and forces sperm out
- archegonia secrete attractive molecules
- sperm swims down neck of archegonium and unites with egg
moss sporophyte develop from zygote (2n process)
- venter of archegonium expands as the zygote is breaking out
- sporophyte is formed from the expanding archegonium
- calyptra and operculum break away from the peristome
- sporocytes are undergoing meiosis in the sporangium to produce spores
- spores are now freed through the peristome from the capsule
asexual reproduction moss (1n process)
- spores grow into protonema
- produces buds which grow into either female or male gametophytes
- undergo fertilization process, restart cycle
Liverworts
phylum hepatophyta
two groups of liverworts
- thalloid liverworts (marchantia)
- leafy liverworts (frullania, tropical 80% of species)
external structure of thalloid liverwort
external: dichotomously forked, robust and 30 cells thick
- upper surface: polygons, pores that stay open
- lower surface: rhizoids
internal strucutre thalloid liverwort
- hollow chambers
- upper: green, pore
- walls: food storage
- columns of chlorenchyma (photosynthesizing cells)
liverwort gametophores
antheridiophore (producing sperm at tip)
archegoniophore (each produce 1 egg, palm tree)
liverwort fertilization (2n)
- young sporophyte formed from fertilized egg
- sporophyte structure:
foot,
seta,
calyptra,
sporocytes
capsule - capsule splits at maturity to release spores
liverwort asexual reproduction (1n)
- spores form female and male gametophores
- most liverworts can reproduce asexually by means of gemmae, which are disks of tissues produced by the gametophytic generation. The gemmae are held in special organs known as gemma cups and are dispersed by rainfall.
- can also reproduce with fragmentation
Hornworts
- phylum anthocerotophyta
- mostly on moist ground, some on trees
structure of hornworts
- thallus
internal:
mucilage filled chamber network (mucus)
N-fixing bacteria (cyanobacteria)
1 chloroplast/cell with large pyrenoid ( store starch)
hornwort sexual reproduction
- gametangia buried in surface of thallus
- fertilization occurs in water
hornwort sporophyte structure
- foot attaches
- no seta
- has meristem (rapidly dividing cells)
- grows upward like a horn
-sporocytes form from spores by meiosis - spores released by splitting of sporophyte
hornwort asexual reproduction
- fragmentation or tubers
