The key difference between glandular and non-glandular trichomes is that glandular trichomes possess a glandular head and secrete secondary metabolites. In contrast, non-glandular trichomes do not process a glandular head and protect plants against UV light.
Trichome is an epidermal outgrowth seen as a tiny hair-like structure on the plant stem and branches. They primarily provide protection to the plant against UV light, insects, transpiration, and freeze intolerance. There may be several types of trichomes as hairs, glandular hairs, scales, and papillae, etc. Some trichomes may be glandular. Glandular trichomes secrete secretions such as metabolites, essential oils, etc. Non-glandular trichomes protect the plant from UV light.
CONTENTS
1. Overview and Key Difference
2. What are Glandular Trichomes
3. What are Non-glandular Trichomes
4. Similarities Between Glandular and Non-glandular Trichomes
5. Side by Side Comparison – Glandular vs Non-glandular Trichomes in Tabular Form
6. Summary
What are Glandular Trichomes?
Glandular trichomes are a type of plant trichomes that secrete various secondary metabolites essential for the plant. They have a glandular head. Functionally, they are specialized tissues. They also have the ability to store or volatilize the secretions at the plant surface. These secondary metabolites are used for pollination, defence, and protection. One of the metabolites secreted by the glandular trichomes is an essential oil, which is very useful in medicines and cosmetics. Moreover, plants that have glandular trichomes secrete metabolites such as terpenoids, phenylpropanoids, flavonoids, and methyl ketones.
Figure 01: Glandular Trichome
Glandular trichomes are found on the surface of about 30% of all vascular plants. There are two main types of glandular trichomes as peltate and capitate. Peltate trichomes secrete only lipophilic substances, while capitate trichomes mainly secrete polysaccharide products.
What are Non-glandular Trichomes?
Non-glandular trichomes are a type of plant trichomes that lack glandular heads. They have a thin apex. Non-glandular trichomes can be unicellular or multicellular. Moreover, they can be branched or unbranched. Most non-glandular trichomes are simple, branchedessential and star-shaped.
Figure 02: Non-glandular Trichome
Functionally, non-glandular trichomes do not participate in the production, storage and liberation of biologically active chemical compounds, unlike glandular trichomes. Instead, they mainly help in the physical protection of plants against biotic and abiotic stresses, forming a protective barrier against low humidity, high temperatures, and solar radiation.
What are the Similarities Between Glandular and Non-glandular Trichomes?
- Various non-glandular and glandular trichomes often cover the surfaces of plant organs.
- The characteristics of glandular and non-glandular trichomes can be used to classify plants.
- They can be unicellular or multicellular and branched or unbranched.
- Both types of trichomes are important for the protection of plants against herbivores and pathogens.
What is the Difference Between Glandular and Non-glandular Trichomes?
Glandular trichomes are the trichomes that posses a glandular head and secrete secondary metabolites. In contrast, non-glandular trichomes are the trichomes that have a thin apex and provide physical protection for plants. So, this is the key difference between glandular and non-glandular trichomes. Moreover, there is a glandular head in glandular trichomes, while non-glandular trichomes lack a glandular head. Besides, the glandular trichomes secrete secondary metabolites that are important for pollination, defence, and protection, while non-glandular trichomes provide physical protection of plants against biotic and abiotic stresses. Therefore, this is the functional difference between glandular and non-glandular trichomes.
Below infographic tabulates the differences between glandular and non-glandular trichomes.
Summary – Glandular vs Non-glandular Trichomes
Trichomes are epidermal appendages derived from the various epidermal cells of stem or leaf. Functionally, they provide physical barriers against external factors, such as animals and pathogens, and also help to restrict the loss of water or to give protection against extreme temperature and ultraviolet radiation. Trichomes can be glandular or non-glandular based on the secretion of secondary metabolites. Glandular trichomes secrete secondary metabolites, while non-glandular trichomes do not secrete secondary metabolites. So, this is the key difference between glandular and non-glandular trichomes.
Reference:
1. Glas, Joris J, et al. “Plant Glandular Trichomes as Targets for Breeding or Engineering of Resistance to Herbivores.” International Journal of Molecular Sciences, Molecular Diversity Preservation International (MDPI), 12 Dec. 2012, Available here.
2. “Trichome.” Wikipedia, Wikimedia Foundation, 20 Jan. 2020, Available here.
Image Courtesy:
1. “Cannabis glandular trichomes” By rodzief – Own work (CC BY 4.0) via Commons Wikimedia
2. “trichome” By Frost Museum (CC BY 2.0) via Flickr