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
How many angels can dance on the head of a pin? about how many could perch at the same time on the head of a pin"". Dorothy L. Sayers argued that the question was "simply a debating exercise" and that the answer "usually adjudged correct" was stated as, "Angels are pure intelligences, not material, but limited, so that they have location in space, but not extension." Sayers compares the question to that of how many people's thoughts can be concentrated upon a particular pin at the same time. She concludes that infinitely many angels can be located on the head of a pin, since they do not occupy any space there: