The Botany of Iceland - 01.12.1942, Side 98

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M. P. CHRISTIANSEN
T. uncatilobum is easily recognizable by its lanceolate leaves, the narrow, hamate,
obtuse lobes, and the small, dense head. By the shape of the leaves it recalls T.
Dahlstedtii Lindb. fil., but the two species are hardly related. On the other hand
it seems to be closely related to T. leucoceþhalum and allied species.
Habitat: Ditches.
Localities: Laugar at Breiðamýri, 27.VII.1937, fr., phot. N.
Geogr. Distr.: Only found in Iceland.
97. Taraxacum concavum M.P.Chr. n. sp.
Spec. orig.: Iceland, Þrastarlunður, 11.VII.1937, leg. M. P. Christiansen. Plate
VIII, fig. 97. Plate XXXVIII, fig. 199.
Planta mediocris. Folia dilute viridia, subglabra, lingulata—lanceolata, sat parum
lobata, petiolis angustis, longis, pallidis, nérvo mediano pallido—paulo roseo, lobis
+ approximatis, latis, sat brevibus, patulis—leviter hamatis, obtusis—acutiusculis,
o—pauce dentatis, inter lobos margine concavo, lobo terminali sat magno, ovato-
triangulari, rotundato—obtuso, lobulis basalibus brevibus, obtusis, antice saepe uni-
dentatis, interlobiis brevibus, integris vel uni-dentatis. Folia interiora latiora, dense
lobata et magis dentata, lobo terminali triangulari-cordato.
Involucrum ellipsoideum, basi ovato-truncatum. Squamae exteriores erecto-pa-
tentes—laxe patentes, ovato-lanceolatae, sensim attenuatae, 3.5—2 X 8—10 mm,
subtus olivaceo-brunnescentes, + purpureae, supra + purpurascentes.
Calathium c. 55 mm latum, radians, planum, sat obscure luteum. Ligulae mar-
ginales c. 3.2 X 20 mm, subtus stria grisea—obscure purpurea notatae, dentibus
obscure purpurascentibus.
Antherae valde polliniferae.
Stigmata luteo-virescentia.
Achenium immaturum laete stramineum, sat aequilatum, 3.2—3.9 mm longum,
1.1—1.3 mm latum, superne parce, late sed breviter spinulosum, ceterum + laeve—
+ tuberculatum, in pyramidem late subcylindricam, 0.9—1.1 mm longam abiens.
Rostrum 9—10 mm longum.
By the shape of its leaves T. concavum recalls T. laeticolor Dahlst., but the form
of the fruit is different; the two species are hardly related. T. concavum, on the
other hand, seems to be closely related to T. leucocephalum and its allies with similar
fruits, pale petioles, etc.
Habitat: Birch-copses, lava-fields.
Localities: Þrastarlunður, 11.VII.1937, fr., phot. S.
Geogr. Distr.: Only found in Iceland.
98. Taraxacum leucocephalum M.P.Chr. n. sp.
Spcc. orig.: Iceland, Brekka, 21.VII.1937, leg. M. P. Christiansen. Plate VIII,
fig. 98. Plate XXXXI, fig. 207.
Planta 25—40 cm alta. Folia cano-viridia, lutescentia, densius araneosa, interdum
pauce purpureo-maculata, lanceolata, profunde lobata, petiolis, sat latis, pallidis—
paulo roseis, nervo mediano pallido, lobis 3—4 utrinque, distantibus, basin versus
latis, in apicem longum, angustum, + patulum, obtusum—acutiusculum attenuatis,
integris—denticulatis, interlobiis sat longis, angustis, uni-subulato-dentatis vel denti-
culatis, lobo terminali sat brevi, hastato vel sagittato, supra medium contracto et in
apicem sat longum, sat angustum, obtusum protracto. Folia interiora dense lobata
et grosse subulato-dentata, lobo terminali magno, sagittato-hastato, supra lobulos
basales robuste dentato-laciniato.
Scapi inferne rosei, superne pallidi—brunnescentes.