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There are a number of important characters
that serve to distinguish Orthilia as distinct from Pyrola:
inflorescence morphology (secund vs. symmetric racemes), anther morphology
(absence vs. presence of tubules), petal morphology (presence vs. absence
of tubercles), nectary morphology (presence vs. absence of a nectariferous
disc), pollen morphology (monads vs. tetrads), style morphology (straight
vs. declinate), and chromosome number (n=19 vs. 23 or 46). Orthilia has the greatest number of unique characters amongst the
possible segregates of Pyrola (Haber & Cruise, 1974) and it
is therefore surprising that many floras, including those treating neotropical
taxa, continue to submerge Orthilia in Pyrola.
Rafinesque (1840) segregated Pyrola secunda as Orthilia, but this name was not accepted until much later, and
Klotzsch (1851) and Garcke (1858), both ignorant of Rafinesque's name,
proposed Actinocyclus Klotzsch and Ramischia, respectively,
for the same unispecific genus. Andres (1923) published a revision
of Ramischia, in which he recognized three species and a number
of varieties; his excessive splitting generally is not followed.
Dorr (1995c) revised the species for the entire neotropical range based
on all available literature and type specimens.
ORTHILIA Rafinesque, Autik. bot. 103. 1840.
Lectotype designated by Dorr (1966): Orthilia parvifolia Rafinesque,
nom. illeg. [=Orthilia secunda (L.) House].
Pyrola Linnaeus sect. Alsoganum S.F. Gray, Nat.
arr. Brit. pl. 2: 403. 1821. Type: Pyrola secunda Linnaeus [=Orthilia secunda (Linnaeus) House].
Pyrola Linnaeus subgen. Orthylia Rafinesque, Med. fl.
2: 70. 1830, p.p. quoad Pyrola secunda Linnaeus, typo excluso.
Lectotype designated by Merrill (1949): Pyrola minor Linnaeus.
Actinocyclus Klotzsch, Monatsber. Königl. Preuss. Akad.
Wiss. Berlin 1857: 14. 1858, non Actinocyclus Ehrenberg, Ber.
Bekanntm. Verh. Konigl. Preuss. Akad. Wiss. Berlin 2: 61. 1837 (=Bacillariophyta). Pyrola Linnaeus subgen. Actinocyclus (Klotzsch) Drude in
Engler & Prantl, Nat. Pflanzenfam. IV(1): 9. 1889. Type: Actinocyclus secundus (Linnaeus) Klotzsch [=Orthilia secunda (Linnaeus) House].
Ramischia Opiz ex Garcke, Fl. N. Mitt.-Deutschland, Ed. 4. 222.
1858. Type: Ramischia secunda (Linnaeus) Garcke [=Orthilia
secunda (Linnaeus) House].
Herbs or subshrubs, erect, to 2.7(-3.3)
dm tall; stems usually single. Leaves alternate or subopposite,
clustered in (1-)2-4 pseudo-whorls at the base of the stem, the pseudo-whorls
often separated by short, but conspicuous internodes; blades slightly
revolute, subcoriaceous; margin crenulate or serrulate (entire),
veins terminating in minute teeth. Inflorescences strongly secund
racemes; scape bracts (0-)4-7. Flowers nodding; calyx
persistent in fruit; corolla as long as or longer than broad, actinomorphic,
petals broadly-ovate, greenish-white, yellowish-green, or white, with two
inconspicuous, basal tubercles above; stamens not or slightly exserted;
filaments flattened or ribbon-like, tapering smoothly to their bases, glabrous,
light-brown; anthers
oblong, wrinkled and papillate, anther tubes absent, the pores large
and elongate; ovary subtended by a 10-lobed, nectariferous disc;
style straight, exserted; stigma pale green, peltate and crateriform,
with 5 prominent, spreading lobes, not subtended by a collar. Fruit
a depressed-globose capsule, light greenish-brown, pendant, the pedicel
and scape eventually becoming erect, the dehiscence incomplete, the margins
of the valves cobwebby; seeds light golden-brown, the testa pitted.
Chromosome number: n=19.
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