Stanhopea oculata

This species is native to Mexico and Central America (perhaps south to Brazil) from elevations of 3,280-9,842 feet (1000 to 3000 m). It is found in foothill and mountain forests and it grows in intermediate to cool conditions.  This is one of the Stanhopea that can easily grow outdoors in coastal southern California and requires shade and high humidity to perform well. The flowers are moderate sized 4.3-4.5 inches (10.8-11.4 cm) wide, and there are many forms that are buff colored to bright yellow.  There is a considerable amount of variation in color and quantity of spots on the petals and sepals with most having a torus shaped (like the letter O) red to purple colored spots.   Several forms have a plethora of intense red to purple spots on the upper hypochile and the epichile. 

Stanhopea oculata inflorescence

The best known characters used to identify this species is the narrow hypochile that is bent at a 90 degree angle, and several dark red eye spots along the hypochile and base of the petals.  The eye spots are what provide us with the epithet “oculata” meaning eyes in Latin.  The most common form of S. oculata sold in southern California has two eye spots on each side of the hypochile and also two eye spots on each petal.  The inflorescences are up to 25 cm long with 5 to 9 flowers per inflorescence.

Stanhopea oculata flower exhibiting
two eye spots at the base of each petal.

Along with the ease of growth and flowering, and the variable flower color, this species is also well known for its fragrance.  This fragrance has been described as vanilla mixed with mint and a hint of cocoa.  If that fragrance sounds too good to be true, it isn’t, it actually comes close to a chocolate peppermint patty candy scent.  The fragrance rivals that of S. tigrina and can easily fill a room, or be detected twenty feet away in my garden.  This is definitely a species that every Stanhopea grower should have at least one form of!

Stanhopea oculata inflorescence

Tigrina Trio

I have three forms of S. tigrina var. nigroviolacea blooming at the same time this summer.  The flowering has been exciting because every day another inflorescence opens and more flowers appear, filling the garden with overwhelming fragrance.  The S. tigrina var. nigroviolacea 'Predator' that I have had for over eleven years has produced an inflorescence with three buds for the first time.  The plant has always produced two buds per inflorescence in the past.

Stanhopea tigrina var. nigroviolacea 'Predator'
exhibiting an inflorescence with three buds

 

Once the flowers open, you end up loosing the effect of
having three buds on the inflorescence

 

Two other forms have also produced several inflorescences that may keep the garden filled with S. tigrina blooms for a whole month!

 

Two more forms of Stanhopea tigrina var. nigroviolacea

 



Stanhopea Inflorescences 2013

After our colder than normal winter, spring has been warmer with close to normal temperatures.  This warm and mild weather has increased the speed of the inflorescence growths for early summer, and it appears that the Stanhopea will be blooming on time this year.  Some Stanhopea are producing additional inflorescences this year, and it is always with a sense of satisfaction that the effort you put into growing a good size plant in one year, pays off with more blooms the following year.

As plants continue to mature they should eventually produce additional growths each year that will lead to an increase in inflorescences.  This may take some time to accomplish and patience is definitely a virtue when growing Stanhopea.  For example the S. tigrina var. nigroviolacea ‘Predator’ from my post last year with eight inflorescences produced thirteen this year.  However, two aborted which happens occasionally due to physical damage or a fungal pathogen.  In addition the S. embreei from last year’s post has three flowers on the inflorescence this year with two more inflorescences coming.  It is good to see a plant that I purchased only two years ago continue to grow well and produced more blooms each year.

S.tigrina nigroviolacea 'Predator"
with eleven inflorescences

S. embreei inflorescence with three buds

If you miss the growth of an inflorescence that is at the top of the growing medium and it seems to be attempting to grow back down into the medium, you may want to insert a plastic tag beneath it to help direct it out of the basket.  I have found that allowing an inflorescence that has already surfaced at the top of the growing medium to grow back down will often result in the failure of the inflorescence to mature and bloom.  Approximately 50% of the inflorescences that grow out of the growing medium and then back in, often rot and never bloom for me.

The following will bloom later in the summer and include a different form of S. tigrina var. nigroviolacea that has not bloomed for me before, an S. oculata that refused to bloom last year, and a new inflorescence is emerging on S. intermedia that I am looking forward to seeing for the first time.



S. intermedia emerging inflorescence

 

Stanhopea Diseases

 

Stanhopea are relatively easy to grow and have few problems when cultured properly.  The most bothersome problem I have found is brown spot and anthracnose in some species and hybrids.  I have provided the following partial list of diseases that I have found susceptible by Stanhopea.  However, there are other diseases and viruses that can affect Stanhopea similar to other orchid genera.  I have included a link at the end of the text for further assistance.

Bacteria:

Acidovorax (Pseudomonas) –This starts as a blister that is small, green/brown and eventually enlarges to a brown or black dried and sunken spot.   Bacterial Brown Spot is a water –borne pathogen that thrives in warm and moist conditions.  Increase air circulation and reduce overhead watering.  Spray the plant with a bactericide (e.g., Physan and copper solutions).

Fungus:

Anthracnose (Colletotrichum and Glomeralla ) This fungus affects the leaves and turns the apex brown and then moves to the leaf base.  This often occurs as bands across the leaf, and for me occur often in the early spring with the weather warms and it is still moist.  This is a fungus that is common when air movement is low, temperatures and humidity is high, and light levels are low.  Use a fungicide such as Cleary’s 3336 to prevent further infections.

Black Rot (Phytophthora cactorum and Pythium ultimum) This is a fungus that is present in some orchids and often attacks new leaves and growth.  This infects the vegetation and causes translucent spots and then the tissue dies (necrosis)and turns black in color.  I have not had a problem with black rot on Stanhopea, but rather other orchids in my collection have been susceptible to this fungus.  Removal of the infected plant parts should be accomplished and standing water should be removed in the growing area to reduce infection.  A fungicide such as Cleary’s 336 can be used to prevent further infections.

Botryis is a fungus that often produces brown spots on orchid flowers which are dead cells (necrosis).  The fungus overwinters on dead and rotting vegetation.  Make sure to keep the growing area clear of dead vegetation and lower humidity below 90 percent.  This is not a serious threat to the orchid plant but disfigures the flowers.

Cercospora Leaf Spot (Cercospora spp.) This often begins as a yellow spot under the leaf and then is noticeable on the upper surface.  This infection spreads through the leaf and the spots are sunken and turn black or brown.  Infected leaves fall prematurely. This is a fungus that is common when air movement is low, humidity and moisture on leaves is high.  Use a fungicide such as Cleary’s 3336 to prevent further infections.

Viruses:

Stanhopea ringspot is a virus that causes yellow spots and rings that are circular or diamond shaped on a green leaf background.   The symptoms occur on older leaves or mature leaves.  This virus has been noted on some Stanhopea, though it  is not common.  I have not had much experience with viruses in my collection and tend to keep my growing area clean and ensure that all my tools are disinfected before each use on a different plant.  If you notice that there are signs of virus on your plant, isolate it from the rest of your collections and seek advice from a competent orchid grower.

For further reading see the AOS Orchid Ailments