Northwest Indian College Welcome to Northwest Plants Northwest Indian College ENVS 201 Spring Quarter 2012

Plant Parts vegetative organs: reproductive organs & structures: stems flowers roots fruits leaves seeds

Today: Leaves

Leaf Features & Functions primary photosynthetic organs may store food (in some species) may shade neighboring competitor species etc.

Leaf Components blade (lamina) petiole (or leaf stalk) stomata & guard cells trichomes (hairs; e.g., stinging nettle and sundew)

bean (Phaseolus) leaf (a simple leaf)

lilac (Syringa) leaf, lower surface (showing stomata and guard cells)

lilac (Syringa) trichome

Leaf Types simple (a single blade; e.g., bean), or compound (more than one blade; several leaflets make up the compound leaf)

Compound Leaves pinnate (or pinnately compound; with odd or even number of leaflets; like a feather) bipinnate (or bipinnately, or twice pinnately compound) palmate (or palmately compound; like the palm of a hand) ternate (or ternately compound; in 3s)

ash (Fraxinus) leaf (odd pinnately compound)

honey locust (Gleditsia) leaf (bipinnately compound)

horsechestnut (Aesculus) leaf (palmately compound)

clover (Trifolium) leaf (ternate)

Leaf Arrangement on Stem alternate (one leaf per node) opposite (two leaves per node) whorled (three or more leaves per node)

paper birch (Betula), alternate leaf arrangement

highbush cranberry (Viburnum), opposite leaf arrangement

tobacco tree (Catalpa), whorled leaf arrangement

Leaf Venation reticulate (or netted, or netlike); may be palmate (e.g., maple) or pinnate (e.g., poplar) parallel (e.g., grasses) dichotomously branched (e.g., ferns and ginkgo or maidenhair tree)

cleared leaf showing reticulate venation

maple (Acer) leaf (palmate venation)

chokecherry (Prunus) leaves (pinnate venation)

corn (Zea) leaves (parallel venation)

ginkgo (Ginkgo) leaf (dichotomously branched venation)

deer fern (Blechnum): a deer fern (Blechnum): a. free (some dichotomous) venation in sterile pinna, b. netted venation of fertile pinna

Leaf Shapes circular (circle-shaped) heart (heart-shaped) lanceolate (long and tapering) linear (long, narrow, parallel sides) etc.

Leaf Margins entire (smooth) wavy serrate (with sharp teeth) doubly serrate (larger teeth with smaller teeth) lobed (with lobes) etc.

Leaf Tips acute (tapering to a straight point) obtuse (non-pointed, rounded) aristate (with a stiff bristle tip) cuspidate (with an abrupt, short, sharp rigid tip) etc.

Leaf Bases truncate (cut off squarely) sagittate (arrow-shaped) stipulate (with stipules) sessile (no petiole) etc.

Leaf Surfaces “top” (adaxial) “bottom” (abaxial)

Surface Features glabrous (smooth) pubescent (with trichomes, hairy) glandular (with glandular trichomes) glaucous (with a waxy, whitish to bluish coating) etc.

Ecological Adaptations xerophytes (plants adapted to arid conditions, with accompanying leaf adaptations; e.g., spines in cacti) mesophytes (typical plants with typical leaves) hydrophytes (plants adapted to aquatic conditions, with accompanying leaf adaptations; e.g., leaf dimorphism)

Other Stuctures & Modifications bracts (leaflike structures) tendrils (modified leaflets; also stipules, petioles or stems) spines (usually a modified leaf, leaf portion or stipule; e.g., cacti; Opuntia also has glochids) various modifications (e.g., insectivorous plants)

bunchberry (Cornus) bracts (white)

pea (Lathyrus) tendril (modified leaflet)

cactus (Opuntia) spines and glochids (small detachable hair-like spines) in areoles (highly specialized branches of cacti)

Venus’ flytrap (Dionaea) traps (with prey)

sundew (Drosera) (with sticky hairs)

butterwort (Pinguicula)

pitcher plant (Sarracenia)

bladderwort (Utricularia) with bladders

Questions & Comments?

Leaves are cool.

Hy’shqe!