Monopodial

Vascular plants with monopodial growth habits grow upward from a single point.

They add leaves to the apex each year and the stem grows longer accordingly.

[1] Orchids with monopodial growth often produce copious aerial roots that often hang down in long drapes and have green chlorophyll underneath the grey root coverings, which are used as additional photosynthetic organs.

They do not have a rhizome or pseudobulbs so species adapted to dry periods have fleshy succulent leaves instead.

With some monopodial species, the stem (the rhizome) might fork into two, but for all monopodial orchids this is not necessary for continued growth, as opposed to orchids with sympodial growth.