Houstonia (plant) Houstonia (plant) Houstonia (bluet) is a genus of plants in the family Rubiaceae. Many species were formerly classified, along with other genera since segregated elsewhere, in a more inclusive genus "Hedyotis". Bluets are often small and delicate. For example, "H. rosea" may grow only one inch tall. Some species are single stemmed and others have multiple stems in bunches. Flowers are blue, purple, lavender, white, or rose, often with shades of one color present in an individual population. Flowers have 4 sepals, colloquially denominated "petals", a salverform corolla with 4 lobes, and an inferior ovary. Some species exhibit heterostyly. The
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