Chapter 29 Flashcards
Land plants evolved from
algae
Salt water to fresh water.
Single spp of freshwater gave rise to terrestrial (Charophytes)
Green algae: chlorophytes never made it to land
Streptophytes
Lumping term of charophytes (Protist) + Land plants
Preventing H2O Loss
Problems of growing on land
Waxy cuticle
Stoma/Stomata
With high UV increased chance of mutation. Plants carried 2 copies of each gene, now bodies are diploid. Selection pressure forces to grow on land
Alternation of generations
Alternate between haploid and diploid portions of life cycle
Haplodipontic
Having multicellular diploid and haploid stages. All land plants are haplodipontic.
Gametophyte
Formed from mitosis of single cell spores. Haploid structure created to house gametes. Multicellular creates gametes. Gametophyte produces gametangia. Fusion of gametes creates zygote and sporophyte
Sporophyte
Diploid structure through meiosis produces spores (Not gametes). Sporophyte produces sporangia, which produces spores. Spores eventually produce gametophytes.
Gametangia
Is an organ or cell in which gametes are produced (Same with multi-celled protists and fungi). (Male) Antheridium and (Female) Archegonium
Antheridium vs Archegonium
Antheridium - Male, develops sperm cells with sterile cells on the exterior.
Archegonium - Female, Eggs with sterile cells surrounding eggs.
Both arise by MITOTIC division of haploid tissue
Dominant Generation
Spends the most time and is the larger part of the organism.
Relative sizes of haploid and diploid generations vary among different plant groups. Early land plants haploid was dominant but with evolution diploid became dominant.
Chlorophytes VS Charophytes
Chlorophytes never made it to land
Charophytes sister to all land plants
Tracheids
Xylem and phloem. Vascularized tissue for moving water and food. Transport cells
Non Vascular plants
Characteristics
Bryophytes
Liverworts (Phylum Hepaticophyta), Mosses (Phylum Bryophyta), Hornworts (Phylum Anthocerotophyta)
No phloem, xylem. Short cannot move against gravity
Gametophytes is dominant generation. (Does photosynthesis)
Sporophyte is dependent to gametophyte (attached to) (Water moves sperm to egg)
Found in all terrestrial environments, prefers moist areas. Prefer areas where they can dominate since they can’t compete for light. Osmosis dependent, diffusion for nutrients.
Phylum Hepaticophyta
Liverworts
20% Lobed, 80% leafy and sort of look leafy and moss like. Some have air chambers for photosynthetic cells having a pore at the top for gas exchange. No stomata, pores are always open. Single celled rhizoids aid in reabsorption of nutrients and anchoring, no roots. Haploid leaf gametophytes (Not true leaf)
Phylum Bryophyta
Mosses
Typically consist of small leaf like photosynthetic structures, no true leaves, no vascular tissues. Leaves do photosynthesis, generally flattened blade 1 cell thick and slightly thick midrib. Do have stomata on sporophyte capsule. Rhizoids in center of moss. Mosses in Arctic, Antarctic abundant most diverse in tropics, sensitive to pollution
Seta
Rhizoid
Foot
Capsule
Sperm
Seta - Sporophyte attachment (Stem like)
Rhizoid - Single cell for reabsorption of nutrients and anchoring (Root like)
Foot - Attachment of sporophyte seta to gametophyte
Capsule - Contains spores after broken.
Sperm - need water for movement
Phylum Anthocerotophyta
Hornworts
Likely earliest land plants but difficult to tell
Sister group to Tracheophytes (Have vasculature)
Sporophytes similar to vascular plant sporophytes
Sporophytes: look like horns rising out of gametophytes, get nutrition from gametophyte, Stomata and photosynthetic, meiosis occurs within horn and spores released along whole length.
Symbiotic with cyanobacteria (Nitrogen)
Seedless vascular plants
Tracheophytes
Sporophyte is dominant generation and gametophytes are very small
Have vascular tissue in sporophyte generation (Xylem/phloem)
Most are homosporous (Spores same size) (Heterosporous = different size spores)
Xylem
Phloem
Lignin
Water = Xylem
Nutrients = Phloem
Lignin - Ring like structure that causes strength and rigidity, produces wood
Lycophyll origins
Euphyll origins
Lycophyll - Stem with vascular tissue has single branching and branch flattens out to form leaf (Microphyll - one vein)
Euphyll - Branching stems with vascular tissue has unequal branching. Photosynthetic “webs” form between branches and become leaf (Megaophyll- multiple veins)
Tracheophytes 3 clades
Lycophytes (Club moss), Pterophytes (ferns and relatives), and seed plants
Lycophytes
Club mosses.
Most species produce spores in cones (Strobili)
Some spp produce spores in sporania.
Small Leaves unbranched veins. Small tree look, tropics and moist temperate. Fossilized were very large, responsible for large quantities of fossil fuels
Sporophylls
Leafs that support sporangia. Common in Lycophytes. Strobili are clusters of highly modified sporophylls.
Monilophytes (Phylum Monilophyta)
Ferns and relatives (Horsetails, whisk ferns)
Early vascularized plants, 12,000 spp mostly ferns.
Older Pteridophytes.
Whisk Ferns
Phylum Monilophyta
Lack roots and leaves. Even forking of green stems. Some have tiny slaps of leaf like tissues, others have appendages that may look leaf like. Gametophyte symbiosis with fungi to acquire nutrients. Dichotomous branching and forked stem. Spores produced in sporangia
Horsetails
Phylum Monilophyta. Class Equisetopsia, Single genus Equisetum
Ribbed, jointed photosynthetic stems that arise from branching underground rhizomes with roots at their nodes (nodules). Haploid spores produced in cones (Sporophylls) carried by air current, land on ground and germinate into photosynthetic gametophytes. Young sporophytes dependent upon gametophyte until produces photosynthetic tissue (then become dominant gen.). Highly reduced leaves (microphylls). Jointed stems hollow with silica deposited. Used to be large 475 MYA. Underground stem (Rhizome)
True Ferns
Phylum Monilophyta
Diploid dominant generation.
Blade - leafy part
Petiole - stem
Frond - stem and leaf
Rhizome - meters long for asexual reproduction
Male and female found on underside of gametangia.
Ferns produce spores in sporangia grouped together into sori (Sorus) on underside. Some sterile.F
Fiddlehead ferns
Coil and uncoil
Unroll and expand
Sporophyte generation.
