Term
All seed plants are heterosporous
Define seed |
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Definition
}mature ovule containing an embryo |
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Term
| Ovule evolution (8 steps) |
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Definition
}megaspore retained in megasporangium (nucellus)
}number of megaspore mother cells reduced to one
}only one of four megaspores survives
}megagametophyte highly reduced, retained in megasporangium
}embryo (young sporophyte) develops within megagametophyte
}integument envelops megasporangium
}apex of megasporangium modified to receive microspores (pollen grains)
}gradually integuments fused until only opening left at apex (micropyle) |
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Term
Define ovule:
>what happens after fertilization
>what do all seeds contain? |
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Definition
}ovule
}nucellus surrounded by one or two integuments with micropyle
}after fertilization, integuments develop into seed coat
}all seeds contain stored food |
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Term
| five phyla of seeds plants with living plants |
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Definition
}arose in late Devonian, 365 mya
}seed plants typically possess megaphylls
}modified into needles or scales in some groups
}Cycadophyta - gymno
}Ginkgophyta - gymno
}Coniferophyta -gymno
}Gnetophyta -gymno
}Anthophyta - angiosperm |
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Term
living gymnosperms - ovules and seeds are exposed on the surface of the sporophylls
>How many species?
>Have four phyla |
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Definition
}840 species
}Four Phyla:
}Cycadophyta
}Ginkgophyta
}Coniferophyta
}Gnetophyta |
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Term
>How many archegonia produced?
>describe fertilization
-is water required?
>antheridia present? |
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Definition
}female gametophyte produces several archegonia
}polyembryony
}fertilization
}water not required
}male gametophyte (pollen grain) transferred to female gametophyte
}pollination
}pollen tube
}no antheridia in seed plants (male gametophyte develops as pollen grains) |
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Term
sperm differ:
>what are they like in conifers and gnetophytes?
>cycads and ginko? |
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Definition
}pollen tube conveys sperm to egg
}
}cycads and gingko: more similar to seedless plants
}pollen tube does not penetrate archegonium
}pollen tube absorbs nutrients for production of sperm |
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Term
Phylum Coniferophyta
>how widespread/important?
>how many species?
>what is it resistant to? |
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Definition
}most numerous, most widespread, most ecologically important gymnosperms
}70 genera, 630 species
}leaves have many drought-resistant characteristics |
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Term
}pines (Pinus)
>how many species?
>what areas do they dominate?
>what adaptations?
>have secondary xylem, phloem? |
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Definition
}90 species
}dominate many areas of N. America and Eurasia
}cultivated in Southern Hemisphere
}leaves adapted for low soil moisture
}thick cuticle
}hypodermis
}sunken stomata
}secondary xylem
}towards inside of vascular cambium
}xylem primarily tracheids
}phloem primarily sieve cells
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Term
Pinus life cycle
>how long?
>where is males on the tree, and where are the female cones?
>where are the micro and megasporangia borne?
>when does pollination occur?
>when does generative cell of male undergo division?
>are there antheridia present in seed plants? |
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Definition
}two years to complete
}microsporangiaand megasporangia borne on separate cones (strobili) on same tree
}usually male on lower branches and female on upper
}pollination
¨occurs in spring
¨pollen grain grows pollen tube into nucellus
¨about a month later, megaspores produced
¨one megaspore becomes megagametophyte
¨very slow development
¨about 15 months after pollination archegonia formed
¨generative cell of male gametophyte undergoes division about 12 months after pollination
¨sterile cell
¨spermatogeneous cell (which then divides to make two sperm cells)
¨remember: no antheridia in seed plants |
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Term
Pinus life cycle continued.
>what happens after 12 months of pollination
>what happens to the pollen tube/sperm
>whats polyembryony |
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Definition
}fertilization
¨about 12 months after pollination
¨pollen tube reaches egg cell in archegonium
¨one sperm cell will fertilize egg
¨usually all eggs fertilized but only one embryo develops fully (polyembryony) |
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Term
Pinus life cycle continued II
>fertilization after 12 months what happens to the pollen tube?
>how many sperms fert. egg?
>how many eggs turn into embryo? |
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Definition
¨about 12 months after pollination
¨pollen tube reaches egg cell in archegonium
¨one sperm cell will fertilize egg
¨usually all eggs fertilized but only one embryo develops fully (polyembryony) |
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Term
Pinus life cycle continued III
>whats going on with the seed?
>generations
>what happens in the second year?
>How do they disperse? |
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Definition
}seed
¨two diploid sporophytic generations
¨seed coat
¨embryo
¨one haploid gametophytic generation
¨food reserve
¨seeds usually shed in fall of second year
¨most winged, wind dispersed
¨some pines require fire to open scales
¨some require birds |
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Term
Phlyum Cycadophyta
>How many species
>what kind of climate found in?
>what kind of sizes generally?
>does it have secondary growth?
>What do they have to do with the Mesozoic?
>How many native to US? |
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Definition
}cycads: 11 genera, 140 species
}palmlike plants, mainly tropical and subtropical
}most fairly large
}distinct trunk covered with leave bases
}true secondary growth
}abundant during Mesozoic
}“age of cycads and dinosaurs”
}only one species native to U.S.
}Zamia pumila |
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Term
Phlyum Cycadophyta Reproductive organs
>what structures?
>what sex?
>pollination is carried out by what? |
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Definition
}conelike structures
}unisexual plants
}insects important in some
}beetles may carry out entire life cycle in cones
}eat pollen
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Term
Phylum Ginkgophyta
>How many living members?
>what shape are the leaves? and what are they called?
>how fast is the tree grow?
>what sex? |
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Definition
}one living member: Ginkgo biloba(maidenhair tree)
}fan-shaped deciduous leaves, dichotomously branching
}slow-growing tree
}changed little over 150 my
}unisexual plants
}female seeds smell foul |
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Term
Phylum Gnetophyta
>How many species?
>what kind of plants does it include? (2).
>what climate? |
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Definition
}Gnetum
}30 species
}trees, climbing vines
}large, leathery leaves
}moist tropics |
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Term
Phylum Gnetophyta - Ephedra
>How many species?
>What do they look like?
>what do they resemble?
>where are they found?
>How many found in US.? |
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Definition
}35 species
}branched shrubs with small, scalelike leaves
}superficially resembles Equisetum
}arid or desert regions
}only genus of gnetophytes found in U.S. |
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Term
Phylum Gnetophyta - Welwitschia
>How many leaves ?
>where are they found?
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Definition
}exposed plant produces two leaves
}most buried in sand
}coastal desert of southwestern Africa |
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Term
Phylum Gnetophyta - share angiosperm like features.
>what shape are the flower clusters?
>xylem vessels?
>archegonia?
>what kind of fertilization?
>what pollinates? |
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Definition
}strobili like flower clusters
}similar xylem vessels
}lack of archegonia
}double fertilization in Ephedra
}insect pollination important |
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Term
| Gymnosperms and Angiosperms |
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Definition
}Kingdom Plantae
}multicellular, sporopollenin, alternation of generations, apical growth
}seed plants
}dominant sporophyte generation
}heterosporous
}non-motile sperm (no water for fertilization)
}conifers and gnetophytes
}no antheridia |
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Term
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Definition
}double fertilization
}although some gnetophytes do, but produce two embryos
}triploid endosperm
}flowers
}fruits
}no archegonia
}3 celled pollen grain (microgametophyte)
}vessel elements |
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