Druse are groups of crystals of calcium oxalate

Calcium oxalate

Calcium oxalate is a chemical compound that forms needle-shaped crystals, known in plants as raphides. A major constituent of human kidney stones, the chemical is also found in beerstone, a scale that forms on containers used in breweries...

, silicates or carbonates present in plants. Calcium oxalate (Ca(COO)₂, CaOx) crystals are found in algae

Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

, angiosperms and gymnosperms in a total of more than 215 families. These plants accumulate oxalate in the range of 3%-80% (w/w) of their dry weight via a biomineralization process in a variety of shapes. Araceae

Araceae

Araceae are a family of monocotyledonous flowering plants in which flowers are borne on a type of inflorescence called a spadix. The spadix is usually accompanied by, and sometimes partially enclosed in, a spathe or leaf-like bract. Also known as the Arum family, members are often colloquially...

have numerous druse, multi-crystal druse and needle shaped raphide crytals of CaOx present in the tissue. Druse are also found in leaves and bud scales of Prunus

Prunus

Prunus is a genus of trees and shrubs, which includes the plums, cherries, peaches, apricots and almonds. There are around 430 species spread throughout the northern temperate regions of the globe. Many members of the genus are widely cultivated for fruit and ornament.-Botany:Members of the genus...

, Roses, Allium

Allium

Allium is a monocot genus of flowering plants, informally referred to as the onion genus. The generic name Allium is the Latin word for garlic....

, Vitus

Vitus

Saint Vitus was a Christian saint from Sicily. He died as a martyr during the persecution of Christians by co-ruling Roman Emperors Diocletian and Maximian in 303. Vitus is counted as one of the Fourteen Holy Helpers of the Roman Catholic Church....

, Morus

Morus

Morus may refer to:* Morus , a genus of trees* Morus , a genus of seabird in the family Sulidae* Thomas Morus, alias Thomas More, a philosopher...

and Phaseolus

Phaseolus

Phaseolus is a genus in the family Fabaceae of about fifty plant species, all native to the Americas.At least four of the species have been domesticated since pre-Columbian times for their beans. Most prominent among these is the common bean, P...

. , . The poisonous substances in druse are thought to be a prevention from herbivorage.

How Druse are Formed

A number of biochemical pathways

Metabolic pathway

In biochemistry, metabolic pathways are series of chemical reactions occurring within a cell. In each pathway, a principal chemical is modified by a series of chemical reactions. Enzymes catalyze these reactions, and often require dietary minerals, vitamins, and other cofactors in order to function...

 for calcium oxalate biomineralization in plants have been proposed. Among these are the cleavage

Bond cleavage

Bond cleavage, or scission, is the splitting of chemical bonds.If the two electrons in a cleaved covalent bond are divided between the products, the process is known as homolytic fission and free redicals are generated by homolytic cleavage the process is known as homolytic fission or homolysis...

 of isocitrate, the hydrolysis

Hydrolysis

Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...

 of oxaloacetate, glycolate/glyoxylate oxidation, and/or oxidative cleavage of L-ascorbic acid. The cleavage of ascorbic acid appears to be the most studied pathway. The specific mechanism controlling this process is unclear but it has been suggested that a number of factors influence crystal shape and growth, such as proteins, polysaccharides, and lipids or macromolecular membrane structures. Druse may also have some purpose in calcium regulation.

See also

• Raphide
• Idioblast
  Idioblast
  Idioblasts are isolated plant cells which differ from neighboring tissues and contain non-living substances. They have various functions such as storage of reserves, excretory materials, pigments, and minerals. They could contain oil, latex, gum, resin, tannin or pigments etc...
  
  
• Phytolith
  Phytolith
  Some plants can take up silica in the soil, whereupon it is deposited within different intracellular and extracellular structures of the plant. After these plants decay, silica is redeposited in the soil in the form of phytoliths , which are rigid, microscopic structures of varying sizes and shapes...
  
  
• protection against herbivory
  Plant defense against herbivory
  Plant defense against herbivory or host-plant resistance describes a range of adaptations evolved by plants which improve their survival and reproduction by reducing the impact of herbivores. Plants use several strategies to defend against damage caused by herbivores...
  
  .