Diversity:  A relatively small group of 10 genera and 12 species that is clearly related to the Ericaceae and often placed within that family as a subfamily (see your text and Thorne's Superorder Dilleniane).

Distribution:  Throughout temperate parts of the World with extensions into the tropics at higher elevations, 2 genera with 3 species in Texas.

Floral structure:

Significant features:  These plants are easily recognized in that they differ from most other plants by the absence of chlorophyll and - at first glance - have the appearance of fungi.  They are fleshy herbs that have taken the fungal association typical of the Ericaceae to an extreme. The mycorrhizal connections allow some taxa of the Monotropaceae to utilize, via a fungal intermediate, the photosynthetic product of other plants.  Other - saphrophytic - taxa appear to tap into products of fungal activity.  In either case, taxa of the Monotropaceae follow a fungal life style, spending most of their time underground only emerging to reproduce via flowers showing a structure similar to that of the Ericaceae and fleshy shoots with reduced, scale-like leaves.
 
 
 

The three Texas species: Pterospora andromeda (pinedrops - left) and Monotropa uniflora (Indian pipe - right), and M. hypopithys (far right)

Hemitomes congestum - 'Coneplant' Northwestern US/Canada

Allotropa virgata - 'Sugarstick', this plant from Washington State
 

More information on the Monotropaceae