740102 Rhododendron lapponicum (L.) Wahlenb.
- Wahlenb., Fl. Lapp.: 104 (1812). - Azalea lapponica L., Sp. Pl.: 151 (1753). Lectotype (LINN): Sweden: "Alpibus Lapponiæ". Herb. Linn. 215.6, right hand specimen (Jonsell in Cafferty and Jarvis 2002b: 753).
(1) 26 (2x) and (2) 52 (4x). - Janaki-Ammal et al. (1950).
Geography: Asian (NE) - amphi-Beringian - North American (N) - amphi-Atlantic (W).
Notes: Yurtsev: Whereas very low-grown plants are typical for most parts of the Arctic, these are replaced by robust, shrubby plants in much of the amphi-Beringian and northwestern North American regions. This difference in growth form is also accompanied by a difference in number of stamens, 5 in the low-grown plants, 10 in the shrubby plants, and mostly 7-8 in intermediates, especially in eastern Siberia and the Russian Far East (see Khokhrjakov and Mazurenko 1991) there treated as [Rhododendron lapponicum and R. parvifolium] and in Alaska and the Yukon Territory (Hultén 1968a). The low-grown plants correspond to R. lapponicum s. str., the tall-grown ones to R. parvifolium Adams.
Elven: Rhododendron lapponicum s. lat. ranges from eastern Siberia (Kharaulakh) throughout North America and Greenland to Scandinavia (from where it was described). There is a gap of more than 100 longitude between its range in Scandinavia and that in eastern Siberia (see, e.g., Hultén 1958, 1968a), whereas the range in North America is nearly continuous. Vinogradova (1980) assigned all arctic Russian material (i.e., in Siberia and the Far East) to R. parvifolium. Malyschev (1997) reported R. lapponicum s. str. (with subsp. alpinum as a synonym) from one region, Kolyma, whereas he assigned the other Siberian material to subsp. parvifolium. Khokhrjakov and Mazurenko (1991) accepted two species and mapped them to be largely sympatric throughout the Russian Far East but only R. lapponicum s. str. to reach the Arctic in Chukotka. Yurtsev (PAF proposal) preferred a collective treatment as R. lapponicum. The Siberian and Beringian plants may be racially different from the northern European, Greenland, and northeastern Canadian ones. I have seen no Alaskan or Chukotkan plants closely resembling the northern Scandinavian (type) ones and suspect that reports of R. lapponicum s. str. from Asia are based on low-grown, alpine and arctic modifications. However, the difference is mainly in size and growth shape. Also the plants in Greenland and northern Europe very often have 7-10 stamens (not 5 as stated by Yurtsev). If there are two races, probably most or all northeastern Asian and Beringian American plants belong to the second race. Both the names "parvifolium" and "alpinum" are based on plants from the Lake Baikal area in southeastern Siberia. We consider them provisionally as synonymous, and then subsp. alpinum has priority for a race. Two races are provisionally entered as subspecies.