C. dickinsonianum/C. irapeanum in nature (with photos)


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Abgeschickt von Jay Vannini am 27 Juni, 2002 um 20:30:45

Antwort auf: Re: C. dickinsonianum/C. irapeanum culture von Marcin Wielicki am 19 Juni, 2002 um 09:06:05:

Cypripedium irapeanum was originally reported as having a fairly widespread distribution in western and central Guatemala, at elevations ranging from 1000 to 3300 m. The populations that occur at elevations >1700 m are subject to periodic frosts of varying intensities from December through February. There are herbarium specimens taken from the outskirts of Guatemala City at ca. 1600 m, but this locality is now urbanized, or covered with Mexican cypress (Cupressus lusitanica) planted in the 1960's. This species is now largely restricted to remote, south-facing slopes of the Sierra de los Cuchumatanes, a mountain range that extends from the border with Chiapas to central Guatemala. There are also relict populations scattered throughout the remaining oak forests of the volcanic cordillera and the central plateau, at least as far east as the department of Jalapa. Plants may occur either as isolated individuals or in fairly large (>100 plants) colonies in lightly disturbed areas. Botanists working in Guatemala in the middle of the 20th century noted that in alpine meadow locations in northwestern Guatemala this species was occasionally locally abundant, with one collector reporting, "...common to the thousands of plants". Plants emerge immediately prior to, or following the first showers of the rainy season. Given the short "window of opportunity" for observing these plants in flower (early June through late July, depending on the locality), it is not surprising that this orchid is not well-known in Guatemala, in spite of being very showy and conspicuous. In Mxico, this species reportedly grows to 1.50 m tall, but I have not seen plants in Guatemala much more than 1.00 m in height. The plants are usually associated with oak or pine-oak forests, in sunny, sloping locations, with very well-drained soils containing fossiliferous limestone. While there are old records of plants on north-facing slopes of volcanoes overlooking the central plateau, all of the plants seen by me over recent years have been on south or southwest-facing hillsides. Both local species of Cypripedium are pubescent on all parts, and some persons report localized irritation/contact dermititis after handling these plants. The severity of the reaction appears to vary amongst individuals; personally, I have not experienced any discomfort after manipulating plants or flowers. The plant in the photo is 62 cm tall.

Cypripedium dickinsonianum was first reported as occurring in sympatry with C. irapeanum in Guatemala by the head of the local university herbarium in the early 1990's. Apparently restricted to the middle elevations (1000 - 1450 m) of the southern face of the Sierra de los Cuchumatanes, its distribution in this country, as presently understood, would suggest little tolerance to frost. Plants appear to favor brilliantly-lit grassy slopes that have shallow seeps running down their faces. This subsurface water may ameliorate the rather lengthy dry season (November-April) in the region where they occur. This species appears to come into flower in early June, and plants bloom sequentially with up to eight flowers per stem. A fact that is often under-emphasized by researchers who have written about this taxon is its diminutive size when compared to its local cogener. Plants begin to bloom at between 20 and 25 cm tall, usually reach 30-35 cm, but may grow as large as 42 cm tall. Plants are most commonly seen as single stems, but may be colonial, with several stems arising from adjoining rhizomes. Flowers are very small for this genus - usually 2-3 cm across, and the pouches are heavily fenestrated. This species is reportedly autogamous, and both newly-opened flowers and developing seed pods were found at this site on June 15th. These plants appear to be very attractive to leaf predators, and a significant number of plants had the apical portions of the stems entirely removed by arthropods and/or mollusks, and the lower leaves were in tatters. The plant in the photo is 25 cm tall.

In spite of occurring in sympatry in both Chiapas, Mxico and western Guatemala, I am not familiar with any reports of hybrids between C. irapeanum and C. dickinsonianum. The significant disparity between flower size apparent in the two species, coupled with the fact that C. dickinsonianum is reportedly autogamous, would suggest it an unlikely event in nature.

Both species (but more so C. irapeanum) have a reputation for being extremely difficult to cultivate.

Climate data: As there is not a weather station at the locality where these orchids were photographed, data available from the closest station (ca. 150 m higher and somewhat wetter) that keeps 40 yr average records are as follows.

Average annual temperature: 19.1 C, Maximum 29.7C, Minimum 7.2C. Average annual precipitation 2259 mm. The rainy season in Guatemala usually begins in May and ends in October. It is bimodal, with peaks in June and September. During July/August there is often a two to three week marked cessation of the rain. January is usually the driest and coolest month.


Jay

Habitat of C.dickinsonianum and C.irapeanum
 

C.dickinsonianum


C.irapeanum



 


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