THE LEAF : TYPES
According to the petiole:
Petiolated leaves are those that have a petiole. This can be different in length from one plant to another.
Sessile leaves do not possess a petiole. The blade expands itself directly from the stem.
Simple leaves show an undivided blade or , in case it has divisions, they do not reach the midrib.
Compound leaves have a fragmented blade,with divisions reaching the midrib. Sometimes each one of these fragments is similar to a single leaf. They are called leaflets.
Entire leaves have a smooth margin.
Sinuate leaves have little curves with smooth edges like waves.
Dentate leaves have little teeth at the margin.
Serrate leaves have little bent teeth like those of a saw.
Lobed leaves have divisions that do not arrive the center of half blade.
Lanceolate leaves : spear-shaped. Gradually extending at the base and lessening to the apex.
Acicular leaves : needle-shaped. Several times longer than wide; ending sharply at the apex.
Ovate leaves : egg-shaped. Wider at the base than the apex.
Cordate leaves : heart-shaped . More extended at the base than the ovate type and with a notch
Hastate leaves: halberd-shaped. Remembering to that old fashioned weapon which was a combination between a spear and a battle-ax. Wider at the base but with lobes ending sharply.
linear leaves: strip-shaped. Several times longer than wide. Not pointed at the apex like in the acicular type.
Parallel-veined leaves : the veins run at the same distance to each other, like in canes.
Pinnate leaves : There is a main nerve, called midrib, from which the other nerves derive, remembering a plume.
Palmate leaves: The nerves diverge from the main point such as the fingers do in the palm of the hand.
opposite: two per node, facing opposite sides of the stem.
whorled: Several leaves disposed at the same level around the stem.
rosulate forming a rosette, like a ring around the stem.
Observe the following plants and choose the suitable answer in each case: