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CH 22 (Conifers # (Transfusion parenchyma is intermixed with tracheids,…
CH 22
Concepts
Seeds originated establishing seeds in spermatophytes
Gymnosperms are naked ovules
Vascular cambium risen independently in some lycophytes
Angiosperms=flowering plants with carpels
Evolution of seeds was preceded by evolution
Fruits are mature carpels
Progymnosperms
Aneurophytales
Varied statures from shrubs
Secondary growth
Some had a cork cambium that produced bark
Primary xylem of stems were protostele
A group from trimerophytes evolved into progymnosperms
Archaeopteridales
Reproduction was heterosporous
Sporangia were terminal on short branches
Stems of Archaeopteris had a siphonostele
Megaspores were released from the sporangia
Abundant wood and secondary phlegm
#
Seeds were not produced
Derived progymnosperm was Archaeopteris
Evolution of seeds
Megasporangium was surrounded by a layer tissue= instrument
Micropyle
Spores cannot be identified with gametophytes
Pollen chamber holding area
Soores can be identified with sporophytes
Seed Ferns
Ring of vascular bundles surrounding pith
Seed fern wood was manoxylic
Were any woody plants with fern like foliage
Earliest seed ferns appeared in the devonian period
Inner cortex contained secretory ducts
Conifers
#
Transfusion parenchyma is intermixed with tracheids
Pollen cones and seed cones
Leaf veins have an epidermis and tissue called transfusion tissue
Trees are monopodial
Leaves are always simple needles or scales
Wood is made of tracheids
Never have rhizomes
Cork cambium
Never vines
Pines have long and short shoots= needle leaves
Diverse
Microspore mother cell undergo meiosis
Pollen cones= simple cones
Development can take as long as a year
Short axis bears leaves= cone bracts
Conifer eggs are gigantic cells loaded w/ carbohydrate and protein
Compound cone= a shoot with axillary buds
Pollen arrives before egg is matured
