Kingdom Plantae: Plant Structure Life Science Chapter 12

Form and Structure Plants: living organisms which are eukaryotic and multicellular, with organized tissues (especially conducting tissues), plastids (such as green chloroplasts), and cell walls containing cellulose. http://videos.howstuffworks.com/hsw/9763-the-world-of-plants-plants-and-the-planet-video.htm

Form and Structure Morphology – the shape or form of an organism Anatomy – the bodily structure of an organism; how the cells and tissues are put together Important because the exterior shape and interior structure of plants often determine where a plant can grow, how it functions, and how it can be used by man.

Plant Organs Most plants have four main types of organs: Roots Stems Leaves Flowers

Plant Organs Determined by their relationships to Nodes: Node – a region where a leaf is or was attached Roots DO NOT have nodes Stems DO have nodes Leaves DO NOT have nodes but are attached to stems at nodes

Roots Two main systems: Tap root – has one or only a few main roots that are thicker and longer than other roots of the plant Lateral roots – smaller roots which branch from the main root Fibrous root – has a cluster of roots that are about equal in size; may branch several times

Stems Two main types of stems: Woody – very hard, firm, and inflexible; capable of supporting a lot of weight; often start as herbaceous but grow into woody stems Herbaceous – softer and more flexible; contains some supporting cells in the stems but not as many as the woody stem; uses Turgor pressure to stand straight

Leaves Three main parts of a leaf: Simple – one leaf Blade – the flat, green part Vein – the water- and sugar-conducting tissues Petiole – the part of the leaf between the node and the blade Simple – one leaf Compound – many leaflets

Leaves Blade edges: Lobed – several indentations within leaf Toothed – edge is saw-like or has jags Smooth – no teeth

Veins Three main types of venation: Parallel – veins run parallel to each other Palmate – veins meet at a common point at the petiole Pinnate – one main vein running the length of the leaf with smaller veins extending to the edge

Petiole The point of connection between the node and the leaf The veins the leaf blade converge and follow through the petiole to the stem

Leaf Arrangements Three common arrangements: Alternate – one leaf per node Opposite – two leaves per node Whorled – three or more leaves per node Leaf arrangements help in identifying plants.

Plant Anatomy Support: Plant: Cellulose creating stiff cell walls Turgor Pressure caused by the presence of water in the cells Plant: All living plant cells contain plastids, though not necessarily green chloroplasts. Some green or red (Tomatoes) chloroplasts, some store starch or oil

Plant Tissues Xylem – made of long, hollow cells; carries water from roots through the stem to the leaves Wood – a collection of layers of xylem that have been formed during several years; tree rings Phloem – carries sugar solution from the leaves to the growing plants

Vascularized bundles – a grouping of xylem and phloem tubules leaves, young plants, and non-woody plants contain vascularized bundles Fibers – long, narrow cells (not hollow) that are VERY strong; often found grouped together to form a fiber tissue Can be used to make rope and cloth

Epidermis – thin, flat cells; effective barrier against loss of water; the outermost tissue of leaves, young roots, and young stems; Secretes a waxy substance that forms the cuticle – protective coating Bark – layer just outside the xylem; innermost layer of bark makes newest xylem and phloem cells

Cork – dead cells with thick cell walls; form a tough, waterproof coating that keeps harmful organisms out and moisture in. Cork cambium – layer of living cells just inside the dead cell; constantly dividing and producing new cells

Major Plant Groups Three main categories: Nonvascular Seedless Vascular Seeded Vascular

Nonvascular Diffusion is used to transport water and other materials Fairly short Live near water and in shady places

Bryophytes Mosses – have structures that resemble leaves and roots but are not true leaves and roots because they do not have vascular tissue Two parts always present: Green part – used for sexual reproduction Rootlike part – anchors plant

Seedless Vascular Plants can grow taller because of the water and material transport system; require water for sexual reproduction Ferns “leaves” are called fronds; appear as coils; spores are produced on the underside of the frond Rhizome – underground stem Roots – grow from rhizome into ground

Seeded Vascular Reproduce by seeds not spores Do not rely on water for sexual reproduction therefore can live in wet or dry areas. Seeds are multicellular; contain a young plant (embryo); abundant energy reserves; barriers for protection Gymnosperm – “naked seed” - limited barriers Pine trees – seeds are exposed Angiosperm – “covered seed” – completely protected seed inside of the fruit http://videos.howstuffworks.com/discovery/30700-assignment-discovery-the-four-types-of-plants-video.htm