Overview
The Canelo Hills ladies'-tresses (Spiranthes delitescens) was listed as endangered without designated critical habitat on January 6, 1997, under the Endangered Species Act of 1973, as amended. Canelo Hills ladies'-tresses is known only from four populations in southern Arizona:
- Canelo Hills - where plants occur within approximately 10 hectares of habitat
- Turkey Creek - where plants occur within approximately 19 hectares of habitat
- San Rafael Valley - where plants occur in approximately 7 hectares of habitat
- Babocomari - where plants occur in approximately 61 hectares of habitat
Members of the Canelo Hills Population were last documented in 2002, when five individuals were counted. Sightings of the Turkey Creek Population were last documented in 2021, when six individuals were counted. Also in 2021, 80 plants were documented from the San Rafael Valley Population. In 2008, members of the Babocomari Population were reported as present. All four populations have been monitored periodically. The largest number of plants seen in any population was 731, in 1999 at the San Rafael Valley Population; the smallest number of plants found was three, in 2019 in the Turkey Creek Population. There are no plants at botanical gardens; however, in 2016, some seed from a single population was preserved and propagation trials are underway. Various threats continue to impact an already small population size, including: a loss or reduction of cienega habitat, a decline in pollinators and animals eating the plant during the flowering and fruiting period.
Scientific Name
Identification Numbers
Characteristics
Physical Characteristics
Canelo Hills ladies'-tresses is a long-lived erect, slender, member of the orchid family Orchidaceae with narrow, tapering, grass-like leaves that grow from the base of the plant and from the stem. The leaves of Canelo Hills ladies'-tresses are up to 18 centimeters long and up to 1.5 centimeters wide. During the monsoon season of summer, Canelo Hills ladies'-tresses form a flowering stalk between 24 and 47.5 centimeters in height, with white flowers that are arranged in a spiral, along and at the top, of the stalk. The flowers are both curved and appear nodding. When Canelo Hills ladies'-tresses plants are dormant, which can happen regularly and over long periods of time, there is a lack of above ground sprout development.
Life Cycle
It is assumed that it takes more than just good substrate, water and light for Canelo Hills ladies'-tresses to germinate, grow and reproduce. Along with other requirements, the correct mycorrhizal symbiont, or symbiotic relationship between plant roots and soil fungi, must be present at the site as well. The seeds of Canelo Hills ladies'-tresses are very small with no food storage, thus requiring nutrients for germination from mycorrhizal symbionts. Canelo Hills ladies'-tresses require periodic low to medium levels of disturbance to remove competing vegetation and maintain the light levels that are needed for germination and growth. These disturbances to the places where they grow also increases the available nutrients which are required for flowering and seed development. Drought stress can lead to mortality of Canelo Hills ladies'-tresses at any portion of its life cycle.
In Canelo Hills ladies'-tresses, there is a complex process from seed germination to adult plant including the enlargement of the embryo into a protocorm, which accumulates carbohydrates, and then allows formation of shoots and roots. Canelo Hills ladies'-tresses plants die back in September or October, overwintering below ground.
Canelo Hills ladies'-tresses are thought to live for many decades, perhaps a century, often in a dormant state underground.
When Canelo Hills ladies'-tresses plants are dormant, there is a lack of above ground sprout development and therefore a lack of photosynthesis and sexual reproduction. The flowering period for Canelo Hills ladies'-tresses is from July to early August during the monsoon rainy season. The primary pollinators of the plant are medium to large, long-tongued bees, especially of the genus Bombus (bumblebees). Canelo Hills ladies'-tresses seed is produced in capsules approximately three weeks after flowers form, typically in late August. Although thousands of seeds are produced by individuals, a relatively small number of seedlings emerge.
Habitat
Canelo Hills ladies'-tresses are found in finely-grained, highly-organic and seasonally or perennially saturated soils in freshwater wetlands, called ciénegas. These ciénegas are located in semidesert grassland or Madrean evergreen woodland at elevations ranging from 1,433 to 1,524 meters. Most ciénegas are associated with springs and are low-gradient wetlands that serve to slow water and trap organic materials and nutrients. Ciénegas are often found in the upper reaches of small drainages or above river channels in a variety of surrounding vegetation communities, and thus are largely protected from scouring floods. Canelo Hills ladies'-tresses require full sun and open growing conditions.
Geography
The range of Canelo Hills ladies'-tresses includes populations in four ciénegas in southern Arizona, three of which are in Santa Cruz County and the fourth in Cochise County.
Timeline
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