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Results tagged “april-04”

Apr 4, 2012: Hibiscus waimeae subsp. hannerae

Hibiscus waimeae subsp. hannerae

Katherine again writes today's entry:

Today, we have a beautiful image of Hibiscus waimeae subsp. hannerae thanks to Anna Kadlec via the Botany Photo of the Day Submissions Forum.

Hibiscus waimeae has two subspecies (sometimes designated varieties): Hibiscus waimeae subsp. hannerae and Hibiscus waimeae subsp. waimeae. Today's featured subspecies is generally smaller overall (including smaller flowers) when compared to the subspecies waimeae, though it has larger leaves. Hibiscus waimeae subsp. hannerae is endemic to Hawaii, and known by the Hawaiian names: Aloalo, Koki'o kea, and Koki'o ke'oke'o, In English, the taxon is commonly known as Kauai white hibiscus, minature Hawaiian white hibiscus, small Kauai white hibiscus, and white Kauai rosemallow. Native Plants Hawaii (see previous link) notes that the genus name stems from "hibiscos, Greek for 'mallow', and the epithet waimeae refers to the Waimea Canyon, Kaua'i where this species is found." That reference also states that Hibiscus waimeae subsp. hannerae blooms year round, although sporadically (often ceasing during winter or early spring), and is unusual among hibiscus in that it is one of only two species (both native to Hawaii) to have fragrant flowers.

According to the U.S. National Tropical Botanical Garden (NTBG) page for Hibiscus waimeae subsp. hannerae, these single flowers last only one day and are "white when open in [the] morning and fade to pink in the afternoon" with a staminal column that is pink to crimson. Easily grown in cultivation (it was previously used as decoration near huts), the taxon is considered endangered. It occurs only in Kaua'i's northwestern valleys of Hanakapi'ai, Limahuli, and Kalihi Wai at elevations of 240 - 1,200m (800 - 3,900ft) (see previous link). Its rarity is in part due to the ease with which Hibiscus waimeae subsp. hannerae hybridizes, and, according to the IUCN Red List, partly due to habitat being "frequently damaged by feral pigs and invaded by introduced plants". The IUCN Red List also notes that the population on Kalihi Wai is seemingly extirpated.

Apr 4, 2011: Eriastrum densifolium subsp. sanctorum

Eriastrum densifolium subsp. sanctorum

Claire Fadul wrote today's entry:

Dale Hameister (Dale Hameister@Flickr) of Redlands, CA provided us with this vibrant photograph of Eriastrum densifolium subsp. sanctorum (taken in early June last year) via the Botany Photo of the Day Flickr Pool. Much appreciated Dale!

Eriastrum densifolium, or giant woollystar, (this particular sub-species is the rarer Santa Ana woollystar) is a common sight in the drier places of California and can usually be found in sandy soils and seasonally dry washes. California is the centre of present-day biodiversity for the Polemoniaceae, or phlox family. Nowadays, the family is mostly found in the New World (approx. 25 genera containing 400 species in North and South America vs. only 3 genera in the Old World). However, what few fossil records exist (Polemoniaceae tend not to grow in places conducive to fossil formation) indicate the presence of Polemoniaceae pollen from Eocene Spain and Pliocene Europe (as well as Miocene California and mid-Eocene Utah).

Eriastrum densifolium subsp. sanctorum is both endemic and endangered in southern California, where it inhabits alluvial washes around the Santa Ana River floodplain. The Seven Oaks Dam is a major threat to the long-term survival of Eriastrum densifolium subsp. sanctorum, as it reduces crucial sediment and new sand deposits the plant relies on for reproduction. Fortunately, a number of people, including professors and students at Cal State Fullerton, are conducting long-term research with an eye to conservation of this rare taxon.

Blooming in the summertime, Eriastrum densifolium subsp. sanctorum has particular pollinators which also share the same habitat requirements of sandy washes. Depending on the location, Burk et al. in a 1989 field study found digger bees, anise swallowtail butterfly, and various hummingbirds to be common pollinators, as well as the "giant flower-loving fly", Raphiomidas actoni subsp. actoni. Some of these species may be mutually dependent on the Santa Ana woollystar, so it is important to continue conservation efforts for the endangered woollystar in order to preserve all constituents of this fragile ecosystem.


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