Plants II Flashcards
2 types of vascular plants
lycophytes and euphyllophytes
what kind of development for vascular plants and what kind of tissue?
apical development makes primary tissue
-seed plants make 2 tissue
lignin
gives wood strength
-plants can’t break it down
Primary tissue
develops from apical meristem and becomes primary plant body (roots, stem, leaves)
secondary tissue
- develops later within primary growth and thickens root and stem
- vascular cambium
3 offshoots from apical meristem
Protoderm –> epidermis (dermal tissue system)
Ground Meristem –> ground tissue (parenchyma, collenchyma, sclerenchyma)
Procambium –> primary xylem and phloem
xylem
water-conducting tissue made of tracheids and vessel elements
-lignified and has fiber
phloem
food-conducting cells made of sieve tube cells and companion cells
epidermis
outermost layer of cells of stem and leaves
-jigsaw puzzle pattern of epidermal cells
stomates + guard cells
regulate gas exchange and decrease water loss in epidermis
trichomes
above ground
-prevent water loss in stem and leaves
root hairs
below ground
-prevent water loss in roots
cortex and pith
primary ground tissues
- cortex is peripheral
- pith is central
arrangement of primary tissue
varies by location in plant
leaf: < o o o >
root / o o \
…… \ o o /
stem /…….o ….. o…… \
……… I o ……………..o I
………. .…. o…… o …./
Shoot anatomy
- where do lateral shoots come from?
- what are the layers of the shoot?
- where do leaves come from?
- what are the layers of leaves?
- axillary buds
- leaf primordium
apical meristem: Tunica (L1 and L2)
Initial layer of corpus (L3)
pith meristem - shoot apex
- epidermis, mesophyll, xylem/phloem
root function
anchors plant
aborbs water and nutrients
cortex in roots
has endodermis (innermost layer of cortex)
- endodermal cells in single layer with suberin-containing casparian strip
- strip is attached to plasma membrane and connects to casparian srips in adjacent cells
- strip blocks movement of water between cells –> water must move thru cell membrane to enter vascular cylinder in center
- as root matures, endodermis becomes sealed with suberin and water doesn’t move into vascular system anymore
Stele: definition and types
- arrangement of primary vascular tissue in stems and roots
- have changed over evolutionary time in dif. plant gps
- protosteles, euteles, alactosteles, siphonosteles
protostele
earliest arrangement observed in vascular plants
- solid core of xylem in center
- still observed in some seed plant roots
siphonostele
solid cylinders of vascular tissue with pith in center
-vascular tissue forms o or c
eustele
pith in center
vascular bundles in circle
-in eudicot stems and monocot roots
alactostele
scattered vascular bundles
in monocot stems
secondary growth
2 meristem 2 tissues
…………………………………………………………….._____ secondary X
X/P ————-vascular cambium ———/_____ secondary P
cortex ——— cork cambium_____________phelloderm
………………………………………………………………….\______cork
vascular cambium
- develops between 1 x/p
- makes 2 x/p
- as growth in diameter continues, pressure on peripheral tissue causes them to slough off
- cells appear stacked
- vascular rays = parenchymatous cells that conduct fluid
cork camium
initiates 1st in cortex as epidermis is disrupted
- produces cork on outside and phelloderm on inside
- cork has lots of suberin
- cork + phelloderm = periderm
- provides waterproof protective layer as epidermis disappears
wood vs bark
inner bark vs outer bark
wood = 2 x bark = 2 p inner = no peridermis outer = lots of peridermis (youngest at center)
Earliest vascular fossils
425 mya
- no leaves
- homosporous
- some w/ hydroids/leptoids, others with x/p
400 mya
-small, nonvascular and early vascular plants
360 mya
- lycopods and pteridophytes mostly
- lycophytes = 70% of our coal
microphylls vs megaphylls
microphylls = made from branching f/ protostele
- no leaf gap or comlex venation
- lycophytes
megaphylls = made f/ vascular bundles
- leaf gap and complex venation
- siphonosteles, eusteles, alactosteles
- all vascular plants besides lycophytes (euphyllophytes)
Homosporous vs heterosporous
homo = makes 1 type of spore that become hermaphroditic gametophytes (more ancient)
hetero = make 2 types of spores (more derived)
-microspores and megaspores
endospore vs exospore gametophytes
- endosporic gametophytes= nonphotosynthetic (usually) and develop inside spore wall (if endosporic, then heterosporous)
- exosporic gamethophytes = photosynthetic (usually) and break out of spore wall to develop independently (homosporous)
lycophytes
-have microphylls
-sporangia are borne next to microphylls
-sometimes condensed into strobilil
“club mosses”
lycopodium
- lycophyte
- homosporous sporophyte with microphylls
- spores produced in sporangia attached to sporophylls clustered together in cones
- gametophyte produces archegonia and antheridia
selaginella
- lycophyte
- heterosporous
- micro and mega spores produced in separate sporangia clustered together loosely on stem or in cones
- endosporic
- embryo dvlps inside femal gametophyte inside megaspore wall
euphyllophytes
- have true leaves
- include moniilophytes and seed plants
Monilophytes
- ferns and fern allies
- sister gp to seed plants
- horsetails, whisk ferns, leptosporangiate ferns
- all shed spores
- typically produce spores in bead-shaped sporangia
horsetails
- 1 genus (equisetum) w/ 15 species
- worldwide distribution
- homosporous sporoophytes
- exosporic, nonvascular photosynthetic gametophytes
- highly reduced leaves
- whorled lateral branches with scale leave, giving bush-like look
whisk ferns
- 2 genera (psilotun and timesipiteris) with 17 species
- homosporous sporophytes
- gametophyte= nonphotosynthetic, underground, with vascular tissue
- worldwide
- frost free
leptosporangiate ferns stem
- rhizome (horizontal stem)
- trunk
- vine
- siphonostele
- develops adventitious roots on underside
leptosporangiate fern leaves
megaphylls with complex venation
- fiddle head development
- grow from rhizomes –> usually the only part above ground
- sporogenus tissue
leptosporangiate fern sporangia
- sori = clusters of sporangia
- insidium = flap covering sporangia
- mostly homosporous (terestrial); some heterosporous (aquatic)
- sporangia distribution differs bt species of fern
ceratopteris richardi
- homosporous aquatic fern
- antheridogens released by germinating spores control sexual differentiation of entire gametophyte generation
