Ericaceae-Neotropical Blueberries
James L. Luteyn and Paola Pedraza-Peñalosa
The New York Botanical Garden




Key to Species

     Orthilia (Ericaceae: Pyroloideae) is a monotypic, circumboreal genus extending south through the cordilleran regions of W North America, with disjunct and isolated populations in the mountains of Mexico and Guatemala.  Like other members of the Pyroloideae, it is principally boreal in its distribution.  Disjunct populations of the sole species, O. secunda (Linnaeus) House, occur in Mexico and Central America.

     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.

Key to Neotropical Species                                                                                               Back to Top

    The only species in the genus is Orthilia secunda.

     This is a version of the taxonomic treatment of Orthilia (Ericaceae: Pyroloideae) by Laurence J. Dorr, modified from "Ericaceae--Part II. The Superior-Ovaried Genera (Monotropoideae, Pyroloideae, Rhododendroideae, and Vaccinioideae p.p.)."  The full treatment including specimen citations may be see in Flora Neotropica Monograph 66: 46-49 (Dorr, 1995c).  This on-line synthesis is published with permission of The New York Botanical Garden and Laurence J. Dorr.


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