Growth Forms

Unicellular

• Organisms that are composed of single cell

• The earliest life was unicellular

• Both prokaryotes and eukaryotes have unicellular members

• e.g., bacteria, Chlamydomonas

Unicellular

Plasmodial

• Organisms that are composed of single visible, blob-like cell

• The large cell is composed of many nuclei. This is called coenocytic

• These organisms are usually probing and exploring the landscape for a food source

• e.g., plasmodial slime molds (Mycetozoa)

Colonial

• Organisms composed of many unicellular organisms "tethered" together

• They communicate with one another to act as a functional large organism

• e.g., Volvox

Multicellular

• Organisms that are constructed of two or trillions of cells

• These cells are connected and communicate with each other for survival

• Both prokaryotes and eukaryotes have multicellular members but they evolved independently

Filamentous

• This growth form is hair-like or strand-like

• There are many cells connected linearly, creating a chain

• When a cell divides, it does so in just one plane or a single orientation

• e.g. Oscillatoria, Spirogyra

Branched filamentous

• This is also a strand-like form of growth but with side branches

• Cells are connected linearly with occasionaly strands that branch off from main filament

• Most growth is in one plane, but when a branch is formed, this requires two planes of division: one continues the filament, and the other creates the branch

Multicellular

Siphonous

• This growth form is tube-like but lacks the connection of many small cells like filamentous forms

• Siphonous organisms usually have a few elongated cells that lack cross-walls

• Because of their larger size, these cells tend to have many nuclei (coenocytic)

• e.g. Polysiphonia

Multicellular

Thalloid

• Having a flattened, splayed-out form of growth

• Thalloid organisms usually grow flat against soil, rocks, or other substrates

• It is found in some macroscopic algae, plants, fungi, and lichens

• Thalloid organisms may be parenchymatous or pseudoparenchymatous

Multicellular

Parenchymatous

• Parenchyma looks like thin-walled, bubble-like cells

• In functionality, plants use these cells to store materials such as water and starches or even house chloroplasts for photosynthesis

• Parenchyma is a type of tissue composed of cells interconnected in three dimensions (i.e., cells are connected above, below, and on the sides of each other)

• Cell division in three planes or orientations creates this three-dimensional construction

• e.g. plants

Multicellular

Pseudoparenchymatous

• Composed of branching, filamentous strands interwoven into a mass that makes up the organism’s body

• It uses the ability to do filamentous growth and then interlace multitudes of strands to create a larger body mass

• It appears parenchymatous but lacks a 3D connection of cells

• e.g., mushrooms