Plants have defenses too!

 We have been learning about the immune system in class to get ready to meet a UBC researcher who studies immunology.  Did you know that plants have defenses too against herbivory?  Some of these defenses are chemical and some are physical.

Foxglove, or digitalis contains toxic chemicals which include cardiac glycosides.  

plants evolved defenses when the first sign of herbivory occurred in evolutionary history. 

Some of these are chemical defenses in the form of poisons. In fact many drugs are derived from plant poisons.  Digitalis is a drug derived from the flower foxglove.   The seed of an apple contains a small amount of  cyanogenic glycoside:  cyanide.  

Plants which contain volatile organic compounds are often very aromatic.  Thyme, Oregano, Rosemary and Lavender are plants which have alot of volatile organic molecules. Not all VOCs are used for herbivory defense.  Some plants use VOCs to attract pollinators. 

Pieris Japonica contains grayanotoxins I, II, III (polyhydroxylated diterpenes) which can cause arrythmias, seizures, vomitting.  

Spines, thorns and hairs also discourage herbivory even silica on horsetails. 

Scavenger hunt 

Take a picture (with your name in it) of the following specimens found in our school grounds:

1.  Foxglove, or Digitalis 

2.   A thorny stem

3.  Hairy leaves

4.  Horsetail. (look at the silica under the microscope).  

5. Lavendula stoechus. (lavender, which has volatile organic compounds)

6.  Pieris Japonica (there is only one specimen I know of on school grounds.