Download Leaf Arrangements

Leaf Arrangements
Types of leaf arrangements include:
Phyllotaxy
Decussate
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Alternate
Basal
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Opposite
Equitant
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Whorled
Rosette
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Phyllotaxy
The spiral arrangement of leaves on the stem is called phyllotaxy.
Red oak (Quercus rubra)
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Phyllotaxy
Leaves spiral around the stem in a regular pattern. It can be described as a
fraction with the numerator being the number of turns around the stem and the
denominator being the number of leaves it takes to return to original leaf position.
4
2
1
0
3
5
Aloe saponaria has a 2/5 phyllotaxy. It produces 5 leaves
before it spirals back to the start position.
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Phyllotaxy
The vertical rank of leaves in a spiral are said to have the same orthostichy.
Leaves 0 and 8 have the same
orthostichy after three spirals
around the axis (3/8).
7
4
3
8
0
5
6
5
1
2
Smoke tree (Cotinus)
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Phyllotaxy
Phyllotaxy indices (like many other spirals in nature) follow a Fibonacci series.
The Fibonacci series consists of a series of numbers that remarkably describe
many spirals observed in nature. The previous pair of numbers sum to the next
number in the series. The series is 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 …
Spirals of disc florets in Purple
coneflower (Echinacea).
Ammonite fossil
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Phyllotaxy
Phyllotaxy follows a numerator and denominator set of offset Fibonacci numbers.
1/2, 1/3, 2/5, 3/8, 5/13, 8/21, 13/34 …
A 3/8 phyllotaxy
A 2/5 phyllotaxy
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Phyllotaxy
As illustrated here with the areolas and spines (modified leaves) of the
cactus Mammillaria, there is actually one set of spirals in a clockwise
direction and one set in a counter-clockwise direction.
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Phyllotaxy
If you start to look for these types of patterns, you will see the clockwise
and counter-clockwise spirals in many different plant structures.
Pineapple (Annas) fruit
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Magnolia fruit
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Lantana inflorescence
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Phyllotaxy
Phyllotaxy can also be expressed by these sets of opposing spirals. Each set of
spirals is called a parastichies. Each parastichies occurs at a regular interval,
but opposite spirals occur in a different number and a different interval.
In this example, there is 1 turn and 3 leaves
in the clockwise direction and 3 turns with 8
leaves in the counter-clockwise direction.
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Tradescantia
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Leaf Arrangements
Alternate- single leaf per node
In the alternate arrangement, a single leaf is attached at each node. The
leaves may be arranged in straight rows or spiral around the stem. The spiral
arrangement of leaves on the stem is called phyllotaxy.
4
2
1
Node
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5
3
Leaf
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Alternate- single leaf per node
There are a few plants that have leaves that occur only on one side of the
stem. Usually the leaves are held on a gently curved stem.
This pattern is called monostichous.
Spiral ginger
(Costus)
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Alternate- single leaf per node
Distichous leaves are arranged in two rows on opposite sides of the stem.
Bald cypress (Taxodium)
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Solomon’s seal (Polygonatum)
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Alternate- single leaf per node
Traveler’s palm (Ravenala madagascariensis) has a spectacular
distichous leaf form.
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Alternate- single leaf per node
Several types of succulent plants display distichous leaves.
Aloe plicatilis
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Gasteria
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Opposite – two leaves per node
Opposite is where a pair of leaves occur at each node. Subopposite is when
some of the leaves are not perfectly paired but the distance between the
nodes are not far enough apart to be considered alternate in arrangement.
Wintercreeper
(Euonymus)
Honeysuckle
(Lonicera)
Subopposite
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Whorled – three or more leaves per node
In the whorled arrangement, three or more leaves arising from the same node
to form whorls of leaves along the stem.
Horsetail (Equisetum)
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Joe pye weed (Eupatorium)
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Lily (Lilium)
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Equitant
Equitant leaves are overlapping as is typical in some Iris.
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Decussate
Decussate leaves are arranged opposite at each node, but each pair of leaves
is oriented at right angles to the pair at the next node.
Crassula perforata
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Thujopsis dolobrata
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Mottlecah
(Eucalyptus macrocarpa)
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Basal
In a basal arrangement, all the leaves arise from the base (crown) of the plant.
Spider plant (Chlorophytum)
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Pineapple lily (Eucomis)
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Rosette
Rosette leaves arranged in a dense, radiating cluster. Rosettes usually form
near the base of the plant.
Mosaic flower (Ludwigia sedioides)
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Mullein (Verbascum)
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