Plant Systems

Plant Tissues and Organs  Like animal cells plant cells can become specialized and form tissues with specific tasks  Healthy plants are always growing and producing new specialized cells  Specialized cells form tissues that are linked together in the plant’s organs (roots, stem, leaf, flower)  Cells responsible for plant growth are called Meristematic cells or meristem.  Meristematic cells are undifferentiated and can form all major types of plant cells

Plant Tissues  Plant tissue can classified into three major groups: Dermal, Ground and Vascular  Dermal tissue forms a covering around the plant’s organs. It is a barrier between the plant and its external environment  Ground tissue is responsible for several roles in a cell including: photosynthesis and support  Vascular tissue is responsible for transporting water, nutrients and sugars throughout the plant. They also aid in supporting the plant as well.

Plant Organs: The Leaf  The leaf’s most important job is to provide a large surface area where photosynthesis can take place  It is a sandwich of photosynthetic (pallisade) cells and vascular tissue between two sheets of epidermal tissue

 Chloroplasts are the green coloured photosynthetic organelles in plants cells  They convert sunlight to glucose for the plant to use as an energy source  Chloroplast contain sac shaped structures called thylakoids which contain light trapping chlorophyll molecules  Thylakoids form stacks called granum Granu m Plant Organs: The Leaf

Plant Organs: The Stem  Stem is used for support and transportation of water, nutrients and sugars  The two major vascular structures in the plant are xylem and phloem  Xylem cells for long straw-like tubes that form pipes to transport water and nutrients from the roots to all other parts of the plant  Phloem cells distribute the sugars and starches produced through photosynthesis to all other parts of the plant.  Xylem and phloem are held together in vascular bundles

The Roots  Roots Anchor a plant to the ground and allow it to take up water and nutrients from the soil  Roots can also function as a storage area (think potato or carrot)  On the outside of roots are tiny hairs that are primarily responsible for absorbing water  Some plants have one major root (tap root = good anchor) while other have fibrous roots that branch out and cover a large surface area (efficient water uptake in upper soil)

The Roots  Inside the outer epidermis a root is the cortex. This is where starch can be stored  Separating the vascular tissue from the cortex is the endodermis and pericyle which help control the transport of minerals and also initiate formation of branch roots  In the middle of the rood are the xylem and phloem which transport water and nutrients

The Flower  The flower is a plant’s reproductive organ  It contains both make and female reproductive organs  Male reproductive cells are called pollen and are produced on structures called stamen which consist of the anther (top) and filament.  Female reproductive cells are called ovum which once fertilized become seeds  These structures are found in the carpel of the flower which consists of the stigma, style and ovary.

Flower Anatomy

Transpiration

Xylem and Phloem Xylem transport water due to capillary action (passive) like a drinking straw Phloem actively transport water due via cell processes. Can have flow in two directions