The Botany of Iceland - 01.12.1942, Qupperneq 65

THE TARAXACUM-FLORA OF ICELAND
291
Achenium c. 4 mm longum, c. 1 mm latum, dilute rubrum (103 D)—brunneo-
rubrum, superne crebre, longe et acute, sat erecto-spinulosum, ceterum dense
spinuloso-tuberculatum, interdum + laeve, in pyramidem c. 0.6 mm longam, sat
conico-cylindricam—cylindricam abiens. Rostrum c. 8 mm longum.
T. isolobum is distinguished by its bright-green, regularly lobed leaves and the
dark-yellow heads. It differs from the other Icelandic species with the same colour
fruits by its narrow, strongly spinose fruit with an almost cylindrical pyramid, and
by the bright, often narrow, transparent- or reddish-margined outer bracts.
The species is no doubt spontaneous.
Habitat: Home-fields, lava-fields, etc.
Localities: Siglufjörður, 14.VII.1935, fr., phot. N.
Geogr. Distr.: Only found in Iceland.
53. Taraxacum repletum Dahlst.
T. croceum Dahlst. subsp. repletum Dahlst. : Om skandinaviska Taraxacum-
former. Bot. Not. 1905.—T. repletum Dahlst.: De svenska arterna av slagtet
Taraxacum. VIII. Spectabilia, 1930, p. 84.—M.P.Chr. Plate IV, fig. 53.
T. repletum Dahlst. differs from T. Davidssonii and nearly allied species by
having plenty of pollen and a fruit with a longer pyramid, up to 1 mm long.
Habitat: Lava-fields, mountain-slopes.
Localities: Cult. in hort. bot. Haun. 425. 1917, fr. Sem. ex Gláma (360 m),
l.VIII.1915 (H. Jónsson).
Geogr. Distr.: Found, outside Iceland, in Sweden.
54. Taraxacum rufescens M.P.Chr. n. sp.
Spec. orig. : Iceland, Reykjahlíð at Mývatn, 25.VII.1937, leg. M. P. Christian-
sen. Plate IV, fig. 54. Plate XXIV, fig. 156.
Planta mediocris. Folia saturate viridia, lutescentia, parce araneosa, lingulato-
lanceolata—lanceolata, integra, mucronata et breviter, late, irregulariter dentata,
dentibus leviter hamatis vel parum profunde lobata, lobis 2—3 utrinque, brevibus,
deltoideis vel angustis, acuminatis, reflexis—hamatis, lobo terminali sat longo, sensim
acuminato, hastato, integro, intcrlobiis latis, sat longis, + dentatis, petiolis sat latis,
pallidis—paulo roseis, nervo mediano pallido—leviter colorato.
Scapi folia valde superantes, fere glabri.
Calathium ignotum.
Achenium dilute rubrum—croceo-rubrum (103 D—128), c. 4.2 mm longum,
c. 1.2 mm latum, fusiforme, superne parce et tenuiter spinulosum, ceterum laeve, in
pyramidem 0.6—0.7 mm longam, latam, conicam sensim abiens. Rostrum 8—9 mm
longam.
T. rufescens seems to be related to T. Davidssonii and nearly allied species, but
differs from these by its fusiform fruits, finely spinous at the summit, and by the
less divided leaves.—The species was cultivated with T. Davidssonii and T. hamidens,
and since its seedlings proved to be very different from the seedlings of the other
two species, it could early be established that it was a good species. Unfortunately
the young plants died owing to an attack of mildew etc., so I have not seen the
species in flower.
It is no doubt spontaneous.
Habitat: Birch-copses.
Localities: Reykjahlíð at Mývatn, 25.VII.1937, fr., phot. N.
Geogr. Distr. : Only found in Iceland.