Schlumbergera

Schlumbergera truncata in bloom.

History. The Schlumbergera is a rainforest-cactus that originated from Brazil.  In Brazil, it is called Flor de Maio because it blooms from April to July, May being the peak of its beauty.  In fact it is a popular Mother's Day flower.   It was named, later on, after Frédéric Schlumberger (1823-1893), a Frenchman, who was a collector of cacti and other succulents (1).  The name "Thanksgiving or Christmas Cactus" was only part of a marketing strategy.  On this part of the globe (northern hemisphere), this plant happens to bloom during this time of the year.  Flowering period coincides with Thanksgiving and Christmas seasons depending on variety. 

Origin.  To be specific, Schlumbergera is known to have come from the tropical rainforest north of Rio de Janeiro. They are epiphytes which mean that they grow on the canopies of trees. Perched up above and on rocks under the shade of taller vegetation, they are adapted to dry conditions and attenuated light.

Photoperiodism.   As I have mentioned many times in previous posts, flower initiation in most plants is triggered by daylength or photoperiod.   Schlumbergera is a photoperiod-sensitive plant.   In my garden, it is regarded as an outdoor plant.  It has been my observation that flower initiation begins sometime in October when daylength is between 9 and 10 hours, therefore they are considered short-day plants (flowering when exposed to daylengths that are shorted than 12 hours).   

Schlumbergera can be manipulated to flower earlier or later by changing the length of light and dark period in a day (24-hour).  Short days can be simulated by subjecting the plants in a prolonged darkness (about 15 hours per day) for a period of one month.  Flowering can also be delayed by reversing the treatment - extend the days by providing few hours of artificial light before sunrise or after sunset.   When the flower buds begin to show, the plants can be brought out to normal conditions.    Artificially inducing the plants to flower is being practiced by commercial growers in order to coincide blooming with the best selling period.  

Flower buds appear on the far end of the stems.

Leaflessness.  These cacti do not have leaves.  Instead they have phylloclades.  Phylloclades are modified branches characterized by being flat and the ability to photosynthesize.  Although they are not leaves they perform the role of leaves for the plant.  Unlike true leaves, phylloclades do not fall (abscise) off with age; instead they turn woody and brownish because a new generation of phylloclades grow from the older ones (just like a lateral branch grow from a more mature branch).  In the absence of leaves, plants do not wilt.  Prolonged exposure to water stress result in shriveling of the plant which is preceded by observed lightening of the green coloration.   Flowers are borne on the apical end of the phylloclades.  

 Soft serration on the phylloclades: characteristic of the Thanksgiving cactus. 

 The perianth at an early stage (sepals, petals, and the tube).

The perianth at opening. 

Reflexed petals.

Observations on the Flowers.  The petals reflex (bend backwards at an acute angle) further exposing the stamens and the anthers.   One peculiar thing that I noticed is that the petals right above the reproductive parts did not reflex upwards.  This tendency of the plant could be nature's way to keep the pollens dry - an adaptation mechanism that is necessary for rainforest plants such as the Schlumbergera species.

Picture taken behind the petals to emphasize the perianth tube.

The stigma prior to opening has an ovoid shape...

 androecium (male parts) and gynoecium (female part)

The stigma extends past the length of the stamens - opening into a claw-like shape.   This is an important feature considering that the flower droops down at opening.  In this position the pollens conveniently falls into the sticky stigma - allowing successful pollination.

The stamens are fused to the perianth tube.

When I opened one of the flowers it came to my attention that the stamens are fused to the perianth tube.  In the more common flowers (take the rose for example), the petals are not attached to either the androecium not the gynoecium.    

Inside the perianth tube.

The flowers are very shimmery. 

Schlumbergera, an epiphyte that has a precise sense of timing... 

She models her bold and shimmery flowers when her rivals are still asleep.

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(1)  http://en.wikipedia.org/wiki/Schlumbergera