Plant of the Week
White Crane's Bill (Geranium richardsonii)
By Walter Fertig
Many books and articles go to great lengths to substitute common names for scientific Latin when treating plant species. This is often done under the pretext that scientific names are too complicated for the lay audience. Thus, people are often surprised to learn that many Latin names are also common names. Some examples include Rhododendron, Philodendron, Fuchsia, Agave, Yucca, and Ficus.
Geranium is another case in point, though in need of some explanation. Botanically, Geranium is a genus in the Geranium family (Geraniaceae) containing about 300 species from temperate and tropical mountain areas across the world. In horticulture, “geranium” refers to cultivated plants in the genus Pelargonium (still in the Geraniaceae) and originally native to southern Africa. Our wild geranium species are often called crane’s-bills because of the superficial resemblance of the erect, unripened fruit to the beak of a crane when it is held straight up during courtship.
White crane’s-bill (Geranium richardsonii) is a perennial geranium found commonly in shady wetlands and streams of western mountains from southern Canada to southern California and New Mexico. This species is distinctive in having five large, white petals with bright pink or purple veins. Other perennial geranium species in the west have pink to purple flowers, though intermediates are sometimes found (these might be hybrids with White crane’s-bill). If you look carefully inside the flower of G. richardsonii, you may notice short hairs cover the lower quarter of the rounded petal. Sticky gland-like hairs usually coat the stems and leafstalks of this species. Under magnification, these hairs are white with a red, ball-like tip. The leaves are also distinctive, having 5-7 deeply divided lobes like a maple, and turn bright red in the autumn.
Most geranium flowers have both male (stamens) and female (ovary) parts, but a small percentage of flowers are functionally female due to abortion of the stamens. Researchers have found that these female flowers are able to devote more energy to fruit and seed production than those that have both sexes and may end up being self-pollinated. The female flowers are often somewhat smaller than bisexual ones and may attract fewer pollinators. Scientists hypothesize that the presence of mixed populations of female and bisexual flowers (technically called gyno-dioecy for crossword puzzle fanatics) is a step on the way to evolving completely separate sexes (dioecy) to ensure cross-pollination.
At maturity, the fruit of the crane’s-bill splits from the bottom into five separate, 1-seeded segments. The fruits initially remain attached at the tip of the style and curl upward from the base. A fruit that splits into multiple smaller fruits is called a schizocarp or “split fruit” (just as a schizophrenic is someone with a “split” personality). The remnant style tip becomes hardened and sharp when fully mature and helps disperse the fruit by getting caught in dense fur (or pant legs) of a passing mammal.