Northwest Indian CollegeENVS 201 Spring Quarter 2012Welcome to Northwest Plants

Plant Partsstemsrootsleavesflowersfruitsseedsvegetative organs:reproductiveorgans & structures:

Today: Leaves

Leaf Features & Functionsprimary photosynthetic organsmay store food (in some species)may shade neighboring competitor speciesetc.

Leaf Componentsblade (lamina)petiole (or leaf stalk)stomata & guard cellstrichomes (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 Typessimple (a single blade; e.g., bean), orcompound (more than one blade; several leaflets make up the compound leaf)

Compound Leavespinnate (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 Stemalternate (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 Venationreticulate (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. free (some dichotomous) venation in sterile pinna, b. netted venation of fertile pinna

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

Leaf Marginsentire (smooth)wavyserrate (with sharp teeth)doubly serrate (larger teeth with smaller teeth)lobed (with lobes)etc.

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

Leaf Surfacestop (adaxial)bottom (abaxial)

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

Ecological Adaptationsxerophytes (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 & Modificationsbracts (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?

Leavesarecool.

Hyshqe!