algal morphology - university of california, santa cruz · 1 algal morphology i. internal thallus...
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Algal Morphology
I. Internal thallus morphologies II. External thallus morphologies III.Algal Growth
Unicells- solitary cells can be motile or non motile ex. Chlamydomonas
Colony- an assemblage of individual cells, variable or predictable number of cells, flagellated or non motile coenobium- predictable number and arrangement of cells ex. Volvox
Uniseriate- cells occuring in a single row
Multiseriate- consisting of several rows of cells in a longitudinal seriesin one or two planes
Filamentous- daughter cells remain attached to each other following cell division forming a chain of cells
Coenocytic/ Siphononous – one large multi-nucleate cell lacking crosswalls
Codium
Utricles -swollen, terminal end of the siphon
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Coenocytic thallus construction - What does this allow? What special issues does it raise?
• Chloroplast movement
• Herbivory – healing • Well developed cytoskeleton • Repairs membrane in 1-2 seconds
Terrestrial Leaf Algal blade
Cortex-pigmented cortical cells
Medulla – unpigmented medullary cells
Limited cell differentiation compared to terrestrial plants…
• cuticle • parenchyma (palisade, spongy) • veins • epidermal • guard cells • stomates
Parenchyma – undifferentiated, isodiometric cells generated by a meristem
Cells division in any plane , not filamentous
Hypnea
Pseudoparenchyma- form of thallus composed of interwoven continuous filaments, superficially resembles parenchyma
Filaments
Sarcodiotheca
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Parenchymatous vs. Pseudoparenchymatous
Mazzaella
Petalonia
Polysiphonous – composed of tiers of vertically elongated cells, transversely arranged, the lateral cells around a central axis (siphon)
central cell surrounded by 4 or more pericentral cells
Polysiphonia
Reds only
Complete Cortication
Ceramium nitens Filament (Central Tissue)
Cortical Cells (Outer Tissue)
Cortication – elaboration of polysiphonous condition where pericentral cells continue to proliferate
Ceramium
Partial Cortication
Cortical Cells (Banded Pattern)
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II. External thallus morphologies
Can affect: - Photosynthesis - Nutrient uptake - Resistance to herbivory - Resistance to physical disturbance (e.g. wave stress)
stipe
holdfast
blade
thallus
Algal morphology:
sori
branching forms non-branching forms
Chaetomorpha Cladophora
Filamentous
Filamentous
Chaetomorpha
Derbesia
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Prostrate / Procumbent: trailing on the ground
Ralfsia Hildenbrandia
“Petrocelis” stage Petrospongium
Foliose = a sheet of cells, blade like, no stipe
Monostromatic – one cell thick Distromatic - two cells thick Polystromatic – many cells thick
Ulva
Bladed- flattened leaf like thallus, may have a stipe Stipitate = has a stipe
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Saccate = sac-like
Botryocladia Halosaccion
Pneumatocysts- -a large float containing gas found in heterokontophyta
-provide buoyancy to lift the blades toward the surface, allowing them to receive more sunlight for Ps
- can hold O2, CO2, CO
Cystoseria osmundacea Sargassum muticum -catenate series -singly
Midrib-thickened longitudinal axis of flattened branch or blade
Alaria fistulosa
Undaria sp.
Midvein-a delicate median line of cells, the blade is thicker through this region
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Tubular- tube of cells, hollow in center
Calliarthron cheiliosporiodes
Geniculum (flexible joint)
Intergeniculum (hard part
between genicula)
Geniculate corallines
• upright
•articulated
•geniculate
Non-geniculate corallines
• crustose
• encrusting
•non - geniculate
Branched- axillary divisions
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Dichotomous/Bifurcate
Pectinate/Secund Whorled/Verticillate
Pinnate-feather-like, regular branching Distichous-branching on both side of the axis, irregular
Opposite Alternate
Monopodial-having a distinct main axis of continuous growth & giving off branchlets Sympodial- apparent main axis does not extend by continuous growth
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stoloniferous/rhizoidal
Holdfast Characteristics
hapterous
holdfast
discoid
Where on the algal thallus does cell division occur? “Meristem” = area of cell division and growth
apical
basal
intercallary
III. Algal growth
Apical growth =Apical cell or apical meristem Multiaxial- several longitudinal medullary filaments, each derived from an apical cell
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Uniaxial- one longitudinal central filament forming the axis
Apical around margin
Intercalary
Intercalary growth
“transition zone”
• Growth in both directions away from meristem • Usually between stipe and blade (or blade and pneumatocyst)
Diffuse growth =
No defined area of cell division or growth; occurs throughout the thallus
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Trichothallic Growth: Cells divide to form hair (filament) above and thallus below (in this case, psuedoparenchymatous polysiphonous…)
Filaments
Thallus
Polysiphonia
Heterotrichous growth – filamentous growth in 2 directions, results in thallus composed of both prostrate + erect components
Upright Form
Prostrate Form (Crustose, spreading)
Lithophyllum congestum