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A Sensitive Mimosa

A Sensitive Mimosa

Sensitive Mimosa

via GIPHY

via GIPHY

As a mother of three children, I’ve found there is no such thing as too many mimosas. Calories don’t count when they’re distributed amongst a group of well-taken too-large-glass-fulls-of-bloody-goodness. We need to make this happen for the sake of humanity.sensitive plant, (Mimosa pudica), also called humble plant, plant in the pea family (Fabaceae) that responds to touch and other stimulation by rapidly closing its leaves and drooping. Native to South and Central America, the plant is a widespread weed in tropical regions and has naturalized elsewhere in warm areas. It is commonly grown as a curiosity in greenhouses. The plant is a spiny subshrub and grows to a height of about 30 cm (1 foot). It has compound leaves and small globular pink or mauve flower puffs. The plant’s unusually quick response to touch is due to rapid water release from specialized cells located at the bases of leaflet and leaf stalks. The leaves reopen in several minutes, and it is thought that this adaptation is a defense against browsing herbivores who may be startled by the movement. In addition to its response to physical stimuli, the leaves also droop in response to darkness and reopen with daylight, a phenomenon known as nyctinastic movement.

Plant

via GIPHY

The leaves are bipinnately compound, with one or two pinnae pairs, and 10–26 leaflets per pinna. The petioles are also prickly. Pedunculate (stalked) pale pink or purple flower heads arise from the leaf axils in mid summer with more and more flowers as the plant gets older. The globose to ovoid heads are 8–10 mm (0.3–0.4 in) in diameter (excluding the stamens). On close examination, it is seen that the floret petals are red in their upper part and the filaments are pink to lavender. Pollens are circular with approximately 8 microns diameter. The leaflets also close when stimulated in other ways, such as touching, warming, blowing, shaking, which are all encapsulated within mechanical or electrical stimulation. These types of movements have been termed seismonastic movements. This reflex may have evolved as a defense mechanism to disincentivize predators, or alternatively to shade the plant in order to reduce water loss due to evaporation. The main structure mechanistically responsible for the drooping of the leaves is the pulvinus. The stimulus is transmitted as an action potential from a stimulated leaflet, to the leaflet's swollen base (pulvinus), and from there to the pulvini of the other leaflets, which run along the length of the leaf's rachis. The action potential then passes into the petiole, and finally to the large pulvinus at the end of the petiole, where the leaf attaches to the stem. The pulvini cells gain and lose turgor due to water moving in and out of these cells, and multiple ion concentrations play a role in the manipulation of water movement.

This characteristic is quite common within the Mimosoideae subfamily of the legume family, Fabaceae. The stimulus can also be transmitted to neighboring leaves. It is not known exactly why Mimosa pudica evolved this trait, but many scientists think that the plant uses its ability to shrink as a defense from herbivores. Animals may be afraid of a fast moving plant and would rather eat a less active one. Another possible explanation is that the sudden movement dislodges harmful insects.In cultivation, this plant is most often grown as an indoor annual, but is also grown for groundcover. Propagation is generally by seed. Mimosa pudica grows most effectively in nutrient poor soil that allows for substantial water drainage. However, this plant is also shown to grow in scalped and eroded subsoils. Typically, disrupted soil is necessary in order for M. pudica to become established in an area. Additionally, the plant is shade intolerant and frost-sensitive, meaning that it does not tolerate low levels of light or cold temperatures. Mimosa pudica does not compete for resources with larger foliage or forest canopy undergrowth. Propagating sensitive plants by seed is the most reliable way to grow new plants. However, the seeds need a little encouragement to germinate. Nick the tough exterior of the seeds with a sharp knife to improve germination success. Afterward, place the seeds in a well-draining potting medium and moisten. Cover the seeds with a small amount of soil and place the pot in a bright, warm location. Mimosa pudica seeds take about a week to germinate. (Source: www.thespruce.com)

 

 

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