A brief pulse of red light will induce a response, provided that the light is sufficiently bright, and conversely, very dim light will work if the irradiation time is long enough. 

This reciprocal relationship between fluence rate and time is known as the law of reciprocity

TLS Online TPP Program

#Id: 9727

#XL - R Botany

The active principle in foxglove (Digitalis sp.) is cardinolide digitoxin, a cardiac glycoside that inhibits ATPase activity and can increase myocardial contraction.

TLS Online TPP Program

#Id: 9728

#XL - R Botany

Laticifers are made of individual cells and can occur either as articulated systems (single cells connected by a small tube) or non-articulated systems (one large syncytial cell).

TLS Online TPP Program

#Id: 9729

#XL - R Botany

Latex are resin terpenoids produced by laticifers is released upon damage and often contains cardiac glycosides which fend off herbivores.

TLS Online TPP Program

#Id: 9730

#XL - R Botany

Conifer resin ducts produces bicyclic monoterpenes such as a-pinene and b-pinene, monocyclic terpenes like limonene and terpinolene, and tricyclic sesquiterpenes, including longifolene, caryophyllene, and d-cadinene, as well as resin acids, which are released immediately upon damage by herbivores

TLS Online TPP Program

#Id: 9731

#XL - R Botany

The specialist caterpillars of the monarch butterfly

(Danaus plexippus) are insensitive to the terpenoid toxins. They feed on milkweed leaves and retain the cardenolides. As a result, most insectivorous birds quickly learn to avoid eating monarch caterpillars and adult monarch butterflies.

TLS Online TPP Program

#Id: 9732

#XL - R Botany

One plant produced sesquiterpene, (E)‐β‐farnesene (EBF), has been considered a potential defense against aphids, since its emission by plants causes aphids to drop off the plant or depart from the feeding site.