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

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

4. Today: Leaves

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

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

7. bean (Phaseolus) leaf (a simple leaf)

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

9. lilac (Syringa) trichome

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

11. 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)

12. ash (Fraxinus) leaf (odd pinnately compound)

13. honey locust (Gleditsia) leaf (bipinnately compound)

14. horsechestnut (Aesculus) leaf (palmately compound)

15. clover (Trifolium) leaf (ternate)

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

17. paper birch (Betula), alternate leaf arrangement

18. highbush cranberry (Viburnum), opposite leaf arrangement

19. tobacco tree (Catalpa), whorled leaf arrangement

20. 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)

21. cleared leaf showing reticulate venation

22. maple (Acer) leaf (palmate venation)

23. chokecherry (Prunus) leaves (pinnate venation)

24. corn (Zea) leaves (parallel venation)

25. ginkgo (Ginkgo) leaf (dichotomously branched venation)

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

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

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

29. 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.

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

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

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

33. 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)

34. 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)

35. bunchberry (Cornus) bracts (white)

36. pea (Lathyrus) tendril (modified leaflet)

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

38. Venus’ flytrap (Dionaea) traps (with prey)

39. sundew (Drosera) (with sticky hairs)

40. butterwort (Pinguicula)

41. pitcher plant (Sarracenia)

42. bladderwort (Utricularia) with bladders

43. Questions & Comments?

44. Leaves
are
cool.

45. Hy’shqe!