Tuesday, January 20, 2015

Two types of Arundina graminifolia [D Don] Hochr. 1910

Tall type
Tall type
dwarf type
dwarf type
tall type

In Puerto Rico you can commonly find on sale two types of Arundina gramminifolia.  One is a tall plant whose stems can easily reach six feet tall or more under good care.  The other is a much smaller plant that rarely seems to reach over three feet tall.  The tall type is a wonderful garden plant as the tall canes produce inflorescences that can stay in bloom for weeks or months.  If given particularly good care, the tall plant can form large clumps with many inflorescences blooming simultaneously.    The sheer size of the tall form means that it is too big for people with limited space on which to grow its orchids.  The dwarf form takes much less space and blooms at a much smaller size.  I have seen plants under two feet tall blooming.  It used to be that the tall form was the only one available but on recent years the dwarf form has become more common.  

The flowers of the two types can be easily told apart.   The flower of the dwarf form is smaller that the flowers of the tall type, although small plants of the tall type can produce smallish flowers.  The form and colors of the lip of the two types are different.  The lip of the tall form is larger and longer in relation to the rest of the flower.  The lip of the dwarf form had more purple lines in the yellow patch of the lip.   In the photos you can see the difference in the lips.

I only have experience cultivating the tall form, which is a tolerant plant that even people that know little about orchids can cultivate successfully.  The dwarf form seems to be equally hardy.   Both plants grow and bloom better when grown in full sun.  The plants I have that are in shadier spots don't bloom as well as those in full sun.

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