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FNA | Family List | FNA Vol. 8 | Saxifragaceae

11. Tolmiea Torrey & A. Gray, Fl. N. Amer. 1: 582. 1840.

Pig-a-back plant [For William F. Tolmie, 1812-1886, surgeon for Hudson’s Bay Company at Fort Vancouver] Pig-a-back plant [For William F. Tolmie, 1812-1886, surgeon for Hudson’s Bay Company at Fort Vancouver]

Douglas E. Soltis, Walter S. Judd, Pamela S. Soltis, Patrick E. Elvander

Herbs, rhizomatous, not stoloniferous; rhizomes sometimes branched, scaly; caudex not cormlike, with persistent leaf bases. Flowering stems erect, leafy, 2.5-70 cm, sparsely to moderately, short to long stipitate-glandular. Leaves in basal rosette and cauline; cauline leaves reduced distally, vegetative shoots sometimes from axillary buds of cauline leaves; stipules present; petiole stipitate-glandular, (adventitious buds usually produced at apices of petioles of rosette and cauline leaves, sometimes forming plantlets); blade ovate, shallowly 5-9-lobed, base cordate, ultimate margins strongly to obscurely, irregularly serrate to nearly dentate, each tooth ending in glandular hair, apex acute (rarely obtuse), surfaces subglabrous to stipitate-glandular; venation palmate. Inflorescences racemes, from axillary buds in rosette, 10-150-flowered, bracteate. ( Pedicels with subtending bracts.) Flowers bilaterally symmetric; hypanthium adnate to ovary only at base for less than 1 mm (ovary appearing superior), free from ovary for 4-5 mm, greenish, ± split to base, (cylindric-funnelform); sepals (persistent), 5, green with variable development of red-purple stripes, (unequal, slightly gibbous at base, stipitate-glandular, 3 dorsal sepals ovate- to elliptic-triangular, apex obtuse to rounded-mucronate, 2 ventral-lateral sepals narrowly ovate-triangular to oblong-triangular, apex acute to acuminate); petals 4, (recurved), greenish to brown-purple, (± linear); nectariferous tissue proximal to stamens; stamens 3, (inserted at apex of hypanthium opposite dorsal sepals, slightly exserted); filaments filiform; ovary superior, 1-locular, (oblong, turbinate, apex 2-cleft, stipitate-glandular), carpels connate proximally; placentation parietal; styles 2; stigmas 2. Capsules 2-beaked, (ovoid, turbinate). Seeds brown to nearly black, subglobose, distinctly muricate. x = 7.

Species 2 (2 in the flora): nw North America.

Although morphologically similar, as reviewed by D. E. Soltis et al. (2007), diploid and tetraploid Tolmiea each meets the criteria for all of the commonly used species concepts: they are reproductively isolated, so they are biological species; they are distinct evolutionary lineages, so the two cytotypes meet the expectations of the evolutionary species concept; each is monophyletic, so both can be considered phylogenetic (apomorphic) species; they are diagnosable on the basis of chromosome number and molecular characters, thus fitting the phylogenetic/diagnosability species concept; and morphological characters distinguish the two cytotypes (although these may be considered cryptic by some), hence they are taxonomic species.

SELECTED REFERENCES Soltis, D. E. 1984b. Autopolyploidy in Tolmiea menziesii (Saxifragaceae). Amer. J. Bot. 71: 1171-1174. Soltis, D. E. and P. S. Soltis. 1988. Electrophoretic evidence for tetrasomic inheritance in Tolmiea menziesii (Saxifragaceae). Heredity 60: 375-382. Soltis, D. E. and P. S. Soltis. 1989. Genetic consequences of autopolyploidy in Tolmiea (Saxifragaceae). Evolution 43: 586-594.


1 Cauline leaves not or only slightly longer than wide, i.e., length-width quotient usually 0.6-1.1 (average 0.9, excluding length of basal lobes); plantlets frequently formed.   1 Tolmiea menziesii
+ Cauline leaves distinctly longer than wide, i.e., length-width quotient 0.8-1.4 (average 1, excluding length of basal lobes); plantlets on leaves sporadically produced.   2 Tolmiea diplomenziesii

Lower Taxa


 

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