Workshop Part 1: Names  Workshop Part 3: Keys   Workshop Part 4: Keys   
Workshop Part 5: Weber Arnica key
   Workshop Part 6: Keys and species

Part 2C: Leaf Margins and Surfaces

TO 2A, LEAF SHAPES
TO 2B, LEAF VENATION AND ARRANGEMENT

Leaf margins

Lobes and sinuses

 Sidalcea neomexicana

 

  Serrations and teeth   

 Betula fontinalis

 

Leaf surfaces

Glabrous

  Goodyera oblongifolia  

 

 Pubescent

   Senecio atratus

 

Leaf modifications

 

Scales

    Juniperus osteosperma   

 

Needles

  Picea pungens

 

Spines

                              Opuntia polyacantha                                      

 

Bracts (The bracts below are edged with fine hairs, i.e., they are "ciliate".)

  Castilleja chromosa     

 

Phyllaries

  Erigeron compositus  

Stem and leaf growth patterns

Appressed: close to or flat against
Ascending: growing upward in a curved fashion
Caespitose: growing in a dense tuft
Declining: curved downward
Decumbent: growing along the ground with an ascending tip
Divergent: spreading
Erect: vertical, not declining or spreading
Ramose: many branched
Recumbent: growing along the ground
Reflexed: sharply declining

Other Stem, Leaf, and Plant Terms

Acaulescent: without a stem, all leaves basal
Adnate: fusion of unlike structures
Cauline: on the stem, as in "cauline leaves"
Caudex: woody base of herbaceous plant
Connate: fusion of like structures
Depauperate: diminutive
Distal: opposite the point of attachment
Herbaceous: fleshy (versus woody)
Internode: distance between point of attachment of leaves on a stem
Involute: rolled inward (as in leaves)
Node: point of attachment of leaves on a stem
Petiole: the leaf stalk
Proximal: at or near the point of attachment
Stipule: tiny leaf-like structures at the base of the petiole
Sub: almost
Revolute: rolled outward (as in leaves)
Rhizomes, rhizomatic, rhizomatous: underground roots with nodes that often give rise to new plants
Stolon: a modified, above ground, horizontal stem that emanates from the base of a plant, roots at its nodes, and gives rise to new plants


Hairs (pubescence)
Hairs are generally called "trichomes" and hairiness is generally referred to as "pubescence".
Plants of the same species will not always have the same level of pubescence.

Canescent (white/gray cast from short hairs)

Tetradymia canescens 

  Strigose (appressed, pointed, short)  

   Ximenesia encelioides  

  

Glandular (sticky, round at tip, often with a noticeable smell)

  Geum macrophyllum

 

 Ribes montigenum

 

Tomentose, villous (dense, woolly, matted, or loose)

 Xanthisma spinulosum 

 

   Pilose (long, soft)

    Pulsatilla patens

 

Stellate (branched hairs which are elevated from the leaf surface)
Notice that the hair structure is most easily observed at the edge of the leaf.

 Draba cuneifolia

 

Hirsute (course, curved)

Clematis hirsutissima

Ciliate (Click to see "Bracts" above)

A few terms for hairs:

Canescent: gray/white appearing because of fine hairs
Ciliate: with marginal hairs
Glandular: with glands, sticky
Hirsute: hairy with course, stiff hairs
Pilose: long, soft, straight hairs
Puberulent: minutely pubescent
Pubescent: hairy
Pustulose: swellings at the base of hairs
Sericeous: silky

Stellate: forked, star-burst-like
Strigose: pointed, straight, appressed hairs
Tomentose: densely clothed with woolly hairs
Trichome: a general term for plant hair
Villous: clothed with long, soft hairs

 

Important reminder

 Just because a species has one or more of the above words in its name, it does not follow that all plants of that species possess those characteristics.  The person who named the plant may have incorrectly named it, may have had specimens that were not typical, or may have named it relative to other plants, e.g., not all plants named "grandiflora" have large flowers; the flowers may be "grand" relative to flowers of other members of that genus.

 

Questions about evolution

Why do plants have hairs?

Why do some plants have hairs and others do not?

Why do some plants have straight hairs and other plants have curved hairs?

Why do some plants in a species have hairs and others of the same species do not have hairs?

Workshop Part 1: Names   Workshop Part 3: Keys   Workshop Part 4: Keys   
Workshop Part 5: Weber Arnica key
   Workshop Part 6: Keys and species