Main Difference -Plumule vs Radicle
Plumule and radicle are the two major parts of an embryo plant. The embryo plant develops into the young plant sporophyte during seedling. The seedling starts with the germination of the seed. Radicle, plumule, and cotyledons are the three parts of the young seedling. Cotyledons are the embryonic leaves. Two types of angiosperms can be identified depending on the number of cotyledons in the seed: monocot and dicot. Monocot contains a single cotyledon while dicot contains two cotyledons in the seed. Gymnosperms contain a varied number of cotyledons. The main difference between plumule and radicle is that plumule is the embryonic shoot while radicle is the embryonic root.
This article looks at,
1. What is a Plumule
– Definition, Structure, Characteristics, Function
2. What is a Radicle
– Definition, Structure, Characteristics, Function
3. What is the difference between Plumule and Radicle
What is a Plumule
The plumule is the rudimentary shoot of the seed embryo, which develops into the first true leaves. It is found above cotyledons during the germination of the seed. Plumule is the growing tip of the epicotyl. Epicotyl is the tiny shoot, which develops into stems, leaves, and flowers of the plant in future. The epigeal germination is the occurrence of the plumule after the growth of cotyledons above the ground. The hypogeal germination is the growth of the plumule above the soil while the cotyledons remain below the surface of the soil. The size and shape of the plumule are varied within species. Most of the plumules are conical. When enough food is stored in the endosperm or cotyledons itself, plumule grows small. In contrast, when little food is stored in the seed, the plumule grows large with well-formed leaves, capturing more sunlight for the synthesis of food by photosynthesis. The development of cotyledons is shown in figure 1. The plumule can be found between two cotyledons.
Figure 1: Plumule between the two cotyledons
What is a Radicle
The radicle is the first part of the embryo, which comes out from the seed during germination. It is the embryonic root of the plant, which develops into the future root of the plant. The emerging of the radicle occurs through the micropyle of the seed. Radicle develops into the soil. While growing into the soil, radicle absorbs water from the soil, which is required by the further development of the embryo. The plumule comes out secondly from the seed, supporting the cotyledons and starts photosynthesis, producing the food required by the further growth of the plant. Two types of radicles are found depending on the directionality of the development of the Radicle: antitropous and syntropous. Antitropous is the growth of the radicle away of the hilum and syntropous is the growth of the radicle towards the hilum. Radicle development in the Aesculus hippocastanum seed is shown in figure 2.
Figure 2: Aesculus hippocastanum
Difference Between Plumule and Radicle
Definition
Plumule: Plumule is the embryonic shoot.
Radicle: Radicle is the embryonic root.
Consequence
Plumule: Plumule grows after the growth of radicle.
Radicle: Radicle comes out first from the seed.
Development
Plumule: Plumule develops into the future shoot, which is the stem and the leaves of the plant.
Radicle: Radicle develops into the future root of the plant.
Growing Towards
Plumule: Plumule grows upwards out of the soil.
Radicle: Radicle grows downwards into the soil.
Color
Plumule: Plumule is less white than the radicle.
Radicle: Radicle is more white than the plumule.
Function
Plumule: Plumule is capable of photosynthesizing in order to produce food for the growing embryonic plant.
Radicle: Radicle is capable of absorbing water from the soil, which is required for the development of the embryonic plant.
Conclusion
Plumule and radicle are two parts of the plant embryo, which are found inside the seed. During the germination of the seed, radicle is developed at first through the micropyle of the seed. The radicle is the rudimentary root of the plant embryo. It grows downward into the soil, absorbing water required by the further development of the embryo. Radicle develops into the root system of the future plant. Plumule emerges secondly to the radicle from the seed. It grows upwards from the soil. Cotyledons are held by plumule. Plumule is capable of photosynthesizing, producing the food required by the growth of the embryo. It develops into the shoot of the future plant, consisting of stem and leaves. However, the main difference between plumule and radicle is in their development into different parts of the future plant.
Reference:
“Parts of a Seed and Their Functions.” CropsReview.Com. N.p., n.d. Web. 01 May 2017.
Image Courtesy:
1. “Seed Blog” by U.S. Department of Agriculture (CC BY 2.0) via Flickr
2. “Aesculus hippocastanum Seed” By JJ Harrison ([email protected]) – Own work (CC BY-SA 3.0) via Commons Wikimedia
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