User:Casssmill/Corallorhiza striata

Corallorhiza striata
Corallorhiza striata, known widely as the striped coralroot, is a small, non-photosynthetic orchid species native to North America. Striata is Latin for "striped" describes the characteristic striped pattern that decorates the stem and flower of C. striata. Its range expands from southern Canada to disjunct populations across montane areas of Mexico, and is found in the America southwest. In particular, it has been found across at least 13 counties in New Mexico and that number could likely grow with systematic surveying. C. striata is fully mycoheterotrophic, meaning it derives all its nutrients through a symbiosis with mycorrhizal fungi. In North America, three distinct varietals are categorized and documented.

Description
Corallorhiza striata, is one of the 11 Corallorhiza orchids endemic to North America. It is a terrestrial orchid that is completely non-photosynthetic and mycotrophic, meaning that it relies completely on mycorrhizal derived nutrients. Like other coralroot orchids, it is leafless and has rhizome root system. The stem of C. striata is reddish-brown in color and covered in small scales and stripes. It can grow to 10-40 cm tall, and its small size and ability to blend in with its surroundings make it difficult to spot in the wild. The fungal associates of C. striata are primarily from the Thelephoraceae family.

Flowers
Flowers forma raceme, growing directly from the stem of Corallorhiza striata. Flowers are small (less than 2 cm) and are striped on all petals and sepals, producing up to 30 flowers per stem. Each flower has three petals and tree sepals, with a small tubular lip at the center that is used to attract pollinators. The lip typically has five bold stripes. Flowers begin to bud in early May, and fully flower in mid-May through mid-July. Its been observed that individuals do not bloom every year, often plants are able to skip one or more years before again appearing aboveground during ideal conditions.

Taxonomy
Corallorhiza striata was first identified in 1840 as Corallorhiza striata by Lindley, but went through a few name changes. After debate, many agreed that three varieties existed, including C. striata var. striata, C. striata var. vreelandii, and C. striata var. involuta. Overall, the striping of C. striata makes it easy to distinguish amongst the Corallorhiza orchids. To identify amongst the varieties special attention must focus on the size of floral parts. C. striata var. striata will have the largest flowers, with lips greater than 7 mm long. C. striata var. vreelandii will have flowers less than 7 mm long and the lips will be wider than 2 mm. C. striata var. involuta will also have smaller flowers that are less than 7 mm long and the lips will be narrow, less than 2 mm wide. In the southwestern United States, C. striata var. vreelandii will be the most commonly observed species.

Using plastid DNA regions from sequences of individuals of the C. striata complex determined distinctive clade clustering of varieties and a closely allied species. Larger flowered varieties of C. striata var. striata were individuals from northern USA and southern Canada. It was sister to the smaller-flowered C. striata var. vreelandii (southwestern USA and Mexico), and a California clade of medium-sized flowers C. striata var. involuta. C. striata and its varieties are an excellent study subject to look for patterns in DNA given its geographic expanse and morphological variation.

Distribution & Habitat
Corallorhiza striata across North America growing terrestrially in montane evergreen and deciduous forests. C. striata can be located among dry, open forests that range from flat to steep and bright to moderately shade between 6900 and 9500 feet. They can grow beneath thin portions of overstory beneath shrubs and rarely occurs in moist environments such as river or streambeds. In the southwestern US, it is found in 8 Arizona counties and 13 New Mexico counties, and likely present but undocumented in more.

Pollination
Corallorhiza striata does not bloom annually but it appears to be pollinated by Coccygonimus pedalis, a parasitic wasp. Wasps were observed visiting flowers and transporting pollen across flowers. Similarly to other Corallorhiza species, self-pollination is also possible, but likely at lower rates than the successful outcrossing accomplished by the wasps.

Mycorrhizae
Like other mycoheterotrophic Corallorhiza orchids, it forms close and specific relationships with ectomycorrhizal fungal associates. C. striata is dependent on these fungal associates for nutrients, as it lost its ability to photosynthesize. A study sequencing 107 individuals of C. striata across 42 populations used plastid DNA from the orchids and ITS sequences of the fungi to test for mycobiont specificity. The study found that nearly all the fungal sequences arose from ectomycorrhizal genus Tomentella, with 95% of the samples matching to a single species T. fuscocinerea, thus concluding the high ranking specificity between orchid and fungal pairs.

Conservation status
At this time, it is not a species of concern as it is widespread throughout the North American continent. In the American southwest, large portions of its habitat are protected within designated wilderness areas and thus protected from destructive anthropogenic activity. Additionally, the presence of C. striata is considered an "ecological indicator" of mature, pristine forest ecosystems across its range.