Sphaerorrhiza

Full name and orig. publication: : Spaerorrhiza Roalson & Boggan, Selbyana 25 (2): 236 (19 Dec. 2005).

Etymology: From the Greek σφαιρ-, sphaer- = of round, globose form (from σφαιρα, sphaira = ball, sphere), and ριζα, rhiza = root, rhizome, in reference to the rhizome with tuber-like swellings.

Synonyms: -

Infrafamilial position: Gesnerioid Gesneriaceae (Gesnerioideae) - Gloxinieae.

Description: Terrestrial perennial rhizomatous herbs. Rhizomes with tuber-like swellings, often breaking apart into propagules. Stem erect or decumbent, glabrescent. Leaves opposite, isophyllous, short-petiolate to subsessile, lamina with 3-7 pairs of veins. Flowers axillary, solitary, showy. Calyx lobes valvate and sealed in bud. Corolla white, lavender or purple, broadly tubular, limb of subequal lobes. Stamens 4; anthers coherent. Nectary annular. Ovary half- to completely inferior. Fruit a dry rostrate capsule. Seeds elliptic, numerous, minute. 

Chromosome number:  

Species number: 2 [S. sarmentiana (Gardn. ex Hook.) Roalson & Boggan, S. burchellii (S.M.Phillips) Roalson & Boggan).

Species names (incl. publication and synonyms): See Skog, L.E. & J.K. Boggan. 2005: World checklist of Gesneriaceae: http://persoon.si.edu/Gesneriaceae/Checklist.

Type species: Sphaerorrhiza sarmentiana (Gardn. ex Hook.) Roalson & Boggan

Distribution: Brazil.

Ecology: Seasonally dormant, surviving and propagating by the unique type of rhizome.

Notes: The two species of the genus, S. sarmentiana and S. burchellii, were formerly placed in the genus Gloxinia. Molecular data showed that they are misplaced not only in that genus, but in the entire tribe Gloxinieae. Therefore, a new genus, Sphaerorrhiza, and a new tribe, Sphaerorrhizeae, have been established (Roalson et al. 2005a,b; Boggan 2006). The most distinctive feature is that the plants produce "lumpy rhizomes" unlike the scaly rhizomes of most other members of tribe Gloxinieae. The rhizomes have tuber-like swellings that easily break apart, with each piece capable of producing a new plant. Another characteristic feature are the valvate calyx lobes sealed in bud. 

Selected references: Roalson, Boggan, Skog, Zimmer, Taxon 54(2): 389-410 (2005a), molec. syst.; Roalson, Boggan, Skog, Selbyana 25(2): 225-238 (2005b), tax.; Boggan, Gesneriads 56 (3): 26-32 (2006), surv.

Bibliography: See Skog, L.E. & J.K. Boggan. 2005. Bibliography of the Gesneriaceae. 2nd edition: http://persoon.si.edu/Gesneriaceae/Bibliography.

Illustrations:

Sphaerorrhiza sarmentiana (Gard. ex Hook.), Roalson & Boggan, type and only species
[formerly Gloxinia sarmentiana Gard. ex Hook.]

Left: Gesneriads 56 (3): 30 (2006), phot. J. Evans
Right: Plant of the week, Smithsonian institution, phot. L. Brothers, http://persoon.si.edu/plofweek.index.cfm

 



last modified: 2007-01-08