Therorhodion
Therorhodion glandulosum
glandular kamtchatka rhododendron
erect to sprawling or procumbent;
twigs rough, with simple, long-stipitate, glandular or eglandular hairs, with or without unicellular hairs, (older twigs without peglike projections).
multicellular, eglandular-hairy (hairs unbranched) and stipitate-glandular-hairy, glabrate with age.
persistent or deciduous, alternate;
petiole absent or nearly so;
blade membranous to chartaceous, margins entire or obscurely serrulate, fringed with eglandular or glandular hairs; (venation brochidodromous, reticulum clear).
often clustered toward distal portions of shoots;
blade elliptic to obovate, sometimes ovate, 1–3.5 × 0.4–1.5 cm, thin, margins ciliate (hairs stipitate-glandular), plane, apex rounded to obtuse or acute, mucronate, surfaces glandular-hairy.
terminal, reduced racemes, (each flower in bract axil);
perulae green, leaflike proximally.
2–3-flowered, sometimes flowers solitary;
axis elongate.
1–4.7 cm, stipitate-glandular-hairy;
bracteoles 2, green, smaller than leaves.
bisexual, bilaterally symmetric;
sepals 5, slightly connate;
petals 5, connate ca. 1/3 their lengths, corolla deciduous, ± rotate;
stamens 10, included, (unequal);
anthers without awns, dehiscent by terminal pores;
ovary 5-locular;
style inserted in slight depression at ovary apex, (curved, long, slender);
stigma capitate.
opening after shoot development, appearing to terminate leafy shoots due to their leaflike bracts;
calyx lobes 7–16 mm, stipitate-glandular-hairy;
corolla purple, upper 3 lobes with darker spots, 16–25 mm, margins smooth, ± glabrous on outer surface, tube ± absent due to slit between lower 2 lobes, lobes 11–24 mm;
stamens unicellular-hairy proximally.
capsular, ovoid, dehiscence basipetally septicidal.
5–11 mm, unicellular-hairy.
ca. 50–100, (brown), ± ellipsoidal, without appendages;
testa smooth.
bud scales (and leaflike inflorescence bracts) stipitate-glandular-hairy.
= 12.
= 24, 26.
Therorhodion
Therorhodion glandulosum
Rhododendron Linnaeus sect. Therorhodion Maximowicz, Mém. Acad. Imp. Sci. Saint Pétersbourg, Sér. 7, 16: 47. 1870; Rhododendron subg. Therorhodion (Maximowicz) Drude
Species 3 (2 in the flora).
Therorhodion is often included within Rhododendron; cladistic analyses (K. A. Kron and W. S. Judd 1990; Kron 1997) indicate that the group lies outside the Rhododendron clade, and it was given generic status by J. K. Small (1914), H. F. Copeland (1943), P. F. Stevens (1971), Kron et al. (2002), and Stevens et al. (2004).
Plants of Therorhodion from the Aleutian Islands and the southern coast of Alaska have leaves that lack or have only sparse stipitate-glandular hairs, and corolla lobes that are hairy outside. In contrast, plants from the Seward Peninsula and lower Yukon River valley have leaves that are obviously glandular-hairy and corolla lobes that are glabrous outside. These two morphological entities often have been recognized as varieties or subspecies (W. R. Philipson and M. N. Philipson 1986; E. Hultén 1927–1930, 1968); they do not intergrade (at least in North America) and are recognized here as distinct, allopatric species. The taxonomy of this group will remain tentative until the genus is revised using modern methods. The third species of the genus, T. redowskianum (Maximowicz) Hutchinson occurs in eastern Asia.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Therorhodion glandulosum is found on the Seward Peninsula and in the lower Yukon River valley.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaf blades (of vegetative branches) eglandular or sparsely glandular-hairy; outer corolla surface hairy, lobe margins ciliolate | T. camtschaticum |
1. Leaf blades (of vegetative branches) glandular-hairy; outer corolla surface ± glabrous, lobe margins smooth. | T. glandulosum |
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