Monotropoideae are united by their more or less herbaceous habit 
(char.#2)and reduced embryo (char.#85). Many members of this clade lack
multicellular hairs on the leaves (char.#22), and this homoplasious 
condition is also resolved as a synapomorphy for members of 
Monotropoideae in the combined analysis (Fig.7). However, in the 
morphological analysis multicellular hairs are hypothesized to have 
been lost twice within Monotropoideae, with Pterospora and Sarcodes 
retaining the plesiomorphic condition (i.e., possessing such hairs), 
and this character optimization is more likely, given the greater 
sampling of members of Monotropoideae in the morphological analysis. 
     Three tribes are recognized within Monotropoideae - the autotrophic
Pyroleae and the mycotrophic Pterosporeae and Monotropeae. Pyroleae are
characterized by the lack of multicellular hairs on their leaves 
(char.#22), separate petals (char.#44) and lack of stamen appendages
(char.#59). Phylogenetic relationships within Pyroleae recently have 
been clarified by Freudenstein (1999). Both Monotropeae and 
Pterosporeae have lost chlorophyll, becoming strongly mycotrophic
(char. #3) with reduced leaves; this condition likely has evolved in
parallel in these two clades. Although the Pterosporeae (Pterospora and 
Sarcodes) are not monophyletic in the morphological analysis (Fig. 3) 
they are monophyletic in analyses that include nrITS (nuclear ribosomal
internal transcribed spacer) and 18S data (Kron, unpublished). The
Pterosporeae are fairly generalized; they have retained many 
plesiomorphic characters, but show the apomorphies of 
non-verticillate leaves (char.#12) and more or less parietal 
placentation (char. #76). Monotropeae are a distinctive clade and can 
be diagnosed by their black coloration upon drying (char. #5), 
non-verticillate leaves (char. #12), lack of multicellular hairs on 
the leaves (char. #22), lack of stamen appendages (char. #59), lack 
of an endothecium (char. #66), more or less parietal placentation
(char. #76), and an extremely reduced embryo (char. #85). Only the 
black coloration and extremely reduced embryo are uniquely derived.

     Evergreen herbs and subshrubs, or echlorophyllous, mycotrophic
herbs. Leaves alternate, spirally arranged, non-ericoid, and convolute 
in bud. Pith homogeneous; leaf epidermal cells not lignified, fibers not
associated with midrib. Indumentum of unicellular or multicellular 
hairs, or none. Inflorescence terminal, racemose or solitary, bracts
present, bracteoles absent, calyx articulated or continuous with the 
pedicel. Flowers (4-)5(-6)-merous, actinomorphic, the calyx and corolla
gamopetalous or polypetalous and sometimes not well differentiated, 
rotate, campanulate, urceolate, or tubular; stamens 10, anthers 
inverting usually just before anthesis, with or without appendages at 
the anther filament junction, endothecium present, but sometimes poorly
developed, pollen shed in monads, tetrads, and/or polyads; ovary 
(4-)5(-8), with axile to parietal placentation with many ovules per 
locule, superior, style usually impressed, stigma sometimes expanded 
and lobed, fruit a loculicidal capsule, berry, or irregularly dehiscent,
seeds with or without tails, testa cells slightly to moderately 
elongated and unthickened, or the cells isodiametric and moderately to
massively thickened on the inner surface, embryo small with two 
cotyledons, or minute and not differentiated.

Pyroleae Dumort., Anal. Fam. Pl. 47: 1829.- Type genus: Pyrola L.
     Herbs or subshrubs, evergreen, with spiral, serrate, non-ericoid 
leaves, convolute in bud. Pith homogeneous; leaf epidermal cells not 
lignified, fibers not associated with midrib. Indumentum of unicellular
hairs, or none. Inflorescence terminal, racemose, bracts present, 
bracteoles none; calyx not articulated with pedicel. Flowers 5-merous, 
actinomorphic. Calyx lobes rather small, ± persistent; corolla
polypetalous, rotate, glabrous; stamens 10, the filaments ± dilated 
basally, straight, usually smooth; anther dehiscing by terminal pores, 
inverting just before anthesis, appendages none, surface usually smooth,
endothecium present, resorbtion tissue present or absent, pollen in 
monads, tetrads, or polyads; ovary 5-locular, with axile placentation 
and many ovules per locule, superior; style impressed, short to quite 
long; stigma usually peltate, sometimes also lobed. Fruit a loculicidal
capsule; seeds with tails at both ends, cells moderately elongated and
unthickened; embryo small, with two cotyledons; n = 13, 19, 23.
[Chimaphila Pursh; Moneses Salisb.; Orthilia Raf.; Pyrola L.]

     Echlorophyllous mycotrophic herbs usually blackening on drying, 
stems annual, with spiral entire sessile non-differentiated leaves 
convolute in bud. Pith homogeneous; leaf epidermal cells not lignified,
fibers not associated with midrib. Indumentum none, rarely of with 
multicellular obscurely glandular hairs. Inflorescences terminal, 
racemose or flower single, terminal; bracts present, bracteoles none, 
basal or apical; calyx articulated with pedicel or not. Flowers 
(4-)5(-6)-merous, actinomorphic. Calyx lobes small, ± persistent; 
corolla sympetalous or polypetalous, campanulate or tubular, or perianth
uniseriate, ± tubular,parts free, basally saccate, glabrous or with 
hairs adaxially; stamens 10, the filaments not dilated basally, 
straight, glabrous or with short hairs; anther dehiscing by terminal 
pores or ± elongated slits, inverting just before anthesis, appendages 
uncommon, small, smooth, paired, at anther-filament junction, or anthers
hippocrepiform, dehiscing by slits, appendages none, surface usually 
smooth, endothecium at most poorly developed, pollen monadinous; ovary 
(4-)5(-8)-locular, with axile to parietal placentation and many
ovules per locule, superior; style usually impressed, little longer
than ovary; stigma barely expanded, rarely lobed. Fruit a loculicidal
capsule, berry or irregularly dehiscent; seeds with isodiametric cells
moderately to massively thickened on inner surfaces, or tailed, with
moderately elongated and unthickened cells; embryo minute, 
undifferentiated, with 30= cells; n = 8, 13, 26, 32 (x = 8, 13?).
[Allotropa A. Gray; Cheilotheca Hook. f.; Hemitomes A. Gray;
Hypopitys Crantz; Monotropa L.; Monotropastrum Andres; 
Monotropsis Schwein.; Pityopus Small; Pleuricospora A. Gray] 
     Note: the interpretation of the morphological nature of the parts 
of the flower of genera like Monotropa is difficult.

     Echlorophyllous mycotrophic herbs, stems annual, with spiral entire
sessile non-differentiated leaves convolute in bud. Pith homogeneous; 
leaf epidermal cells not lignified, fibers not associated with midrib. 
Indumentum of multiseriate-stalked glandular hairs. Inflorescences 
terminal, racemose; bracts present, bracteoles none; calyx articulated 
with pedicel. Flowers 5-merous, actinomorphic. Calyx lobes medium, ± 
persistent; corolla sympetalous, urceolate, glabrous; stamens 10, the 
filaments not dilated basally, straight, smooth; anther dehiscing by 
slits widening considerably apically, inverting some time before 
anthesis, appendages long, strongly papillate, paired, at 
anther-filament junction, surface papillate, endothecium present, 
pollen monadinous; ovary 5-locular, with axile and partly intruded 
parietal placentation, many ovules per locule, superior; style 
impressed; stigma barely expanded. Fruit a loculicidal capsule; seeds
with a tail at one end, cells slightly elongated and unthickened; embryo
minute, unifferentiated, with 30-40 cells; n = 8.[Pterospora Nutt.; 
Sarcodes Torrey,]