Each Seed Has Its Own Parachute

December 04, 2017

Araujia sericifera dispersal of seeds drom a dry pod

Araujia sericifera seed carried by parachute (1)

Photographer: Menashe Davidson 
Summary Author: Menashe Davidson 

Araujia sericifera is a non-native weed species found in the Sharon region of Israel and elsewhere in the Middle East. This beautifully designed plant has but one objective -- to carry out its invasive behavior everywhere it can. Also called the cruel plant its dense foliage prevents light and nutrients from reaching native trees and shrubs, eventually smothering them. Though I've implemented all available measures to control it (pulling by hand, digging it out, using weed killing sprays), it persists despite the efforts of this frustrated farmer. A single vine of A. sericifera possesses hundreds of fruit pods, and when each pod is mature, it splits open, releasing 400 or so tiny seeds, each about 4-7 mm in length with a tuft of silky hairs approximately 25-30 mm in length. 

In fact, the Latin name sericifera of this species refers to the silky hairs attached to the seeds. The parachutes like hairs enable the seeds to be widely dispersed even with relatively weak winds. Seeds are viable for at least 5 years.

The photo at top shows a dry seedpod of A. sericifera; the seeds are connected to the thickened part of the flower stem (the receptacle). Matured seeds have their parachute in place, ready to be picked up by the first wind gust. In 24 hours, all of the seeds from this pod were dispersed. The bottom photo shows a single seed floating in the air, carried by its parachute.  Note the iridescence displayed by the silky hairs. Photos taken during the morning of August 23, 2017. 

Photo Details: Top: Camera Make = Apple: Camera Model = iPhone 6s; Exposure Time (1 / Shutter Speed) = 1/262 second; Lens F-Number / F-Stop =  ƒ/2.2; ISO Speed Ratings = 25; Shutter Speed (Exposure Time) = 1/262.4 second; Aperture = ƒ/2.2. Bottom: Camera Model = NIKON D7100; Exposure Time = 10/5000 second; F-Stop =  ƒ/16; ISO Speed Ratings = 1250.