Houstonia (plant) fruit is an often roughly cordate capsule enclosing many seeds and which usually dehisces via a suture across its apex. "Houstonia" consists of 20 species native to North America. Another 5 species are classified in the genus "Stenaria"; "Houstonia" without "Stenaria" is paraphyletic. Close relatives of the genus are "Oldenlandia microtheca" and, more distantly, "Arcytophyllum". Its members superficially resembles species of the genus "Myosotis" (Forget-me-nots), but are distinguished from the latter by having only 4 sepals (petals) instead of 5. Species accepted as of May 2014 are: Houstonia (plant) Houstonia (bluet) is a genus of plants in the family Rubiaceae.
Plant defense against herbivory reproduction. Many models have been proposed to explore how and why some plants make this investment in defenses against herbivores. The optimal defense hypothesis attempts to explain how the kinds of defenses a particular plant might use reflect the threats each individual plant faces. This model considers three main factors, namely: risk of attack, value of the plant part, and the cost of defense. The first factor determining optimal defense is risk: how likely is it that a plant or certain plant parts will be attacked? This is also related to the "plant apparency hypothesis", which states that a plant