What does the word phyllotaxis mean?
arrangement of leaves
1 : the arrangement of leaves on a stem and in relation to one another.
What causes phyllotaxis?
The phyllotactic pattern therefore results from a dynamic interaction between existing and newly initiating organ primordia on the flanks of the SAM, mediated by actively transported auxin, such that new primordia emerge at sites of high auxin concentration and maintain a minimum distance from each other by depleting …
What is a Distichous leaf?
distichous. / (ˈdɪstɪkəs) / adjective. (of leaves) arranged in two vertical rows on opposite sides of the stem.
What are the four pattern of leaf arrangement?
Leaves are classified as either alternate, spiral, opposite, or whorled. Plants that have only one leaf per node have leaves that are said to be either alternate or spiral.
What does the word phyllo mean?
: extremely thin dough that is layered to produce a flaky pastry.
What is Palmately compound leaf?
A palmately compound leaf has its leaflets radiating outwards from the end of the petiole, like fingers off the palm of a hand. Examples of plants with palmately compound leaves include poison ivy, the buckeye tree, or the familiar house plant Schefflera sp. (commonly called “umbrella plant”).
Why is 137.5 The golden angle?
As plants grow, these fractions often transition according to simple rules related to Fibonacci sequences. This mathematical regularity originates from leaf primordia at the shoot tip (shoot apical meristem), which successively arise at fixed intervals of a divergence angle, typically the golden angle of 137.5°.
What is an opposite leaf?
In opposite-leaved plants, the leaves are paired at a node and borne opposite to each other. A plant has whorled leaves when there are three or more equally spaced leaves at a node.
What is Lanceolate leaf?
Definitions of lanceolate leaf. a leaf shaped like a lance head; tapering to a point at each end. type of: simple leaf. a leaf that is not divided into parts.
What is Phyllotaxis and leaf Venation?
When two or more leaves are borne on the same node, the arrangement is known as cyclic phyllotaxy. It may be of two types: Opposite and whorled. b) Whorled or verticillate: When more than two leaves are developed at each node forming a circle or whorl, the arrangement is known as whorled or verticillate phyllotaxy.
What is the main vein of a leaf known as?
the midrib
A leaf is often organized with one main vein running down the middle of the blade. This vein is called the midrib.
What are the 3 types of leaf arrangements?
Leaf Arrangement Leaves are classified as either alternate, spiral, opposite, or whorled. Plants that have only one leaf per node have leaves that are said to be either alternate or spiral. Alternate leaves alternate on each side of the stem in a flat plane, and spiral leaves are arranged in a spiral along the stem.
Who are the characters in a series of Unfortunate Events?
A Series of Unfortunate Events is a series of thirteen children’s novels by Lemony Snicket. If you have not read anything about the Baudelaire orphans, then before you read even one more sentence, you should know this: Violet, Klaus, and Sunny are kindhearted and quick-witted, but their lives are filled with bad luck and misery.
Are there any examples of phyllotaxis in nature?
First, that the plants have infinite leaves, and, second, that maximum sun exposure is the only factor that determines leaf placement. Neither of these apply, but a divergence angle of 137.5 degrees is still most commonly observed in nature ( Tung 14-15) Examples of Golden Ratio-Based Phyllotaxis.
Which is the most irrational number in phyllotaxis?
Divergence Angles and Phyllotactic Ratios. Earlier, we determined that the golden ratio is the most irrational number, and therefore we arrive at a divergence angle of 360/ (phi) = 222.5, or, equivalently, 360-222.5 = 137.5 degrees, which is the most prevalent angle observed ( Tung 14 ).
What is the phyllotactic ratio of a leaf?
“Botanists define the phyllotactic ratio as the fraction of a circle through which a new leaf turns from the previous (older) leaf” (Tung 14). In the case of a 137.5-degree divergence angle, the ratio is 1/phi, which is approximately 0.618, as we saw here.