5 
Plants suppressed by other plants. 
composed sympodially of several axillary rosettes) has the shape of 
a shallow cup or of a bird’s nest (Text-Fig. 1, b, c ), in the centre of 
which the leafless stem arises. A single individual (viz., the 
flowering stem, sometimes two or three together, with the—simple 
or compound—rosette) has generally about twenty green leaves, 
or even twice as many, besides the dead brownish ones from the 
preceding year. All these leaves are bent outwards at the very 
base (Fig. 1, a), as soon as they become full-grown. In June and 
July there are still young, soft leaves in the middle, standing up 
close to the inflorescence ; but in August they are all spreading 
rigidly outwards. 1 They spread at an angle of 40—90° to the 
perpendicular and force away all the surrounding herbs and grasses, 
except the adjoining rosettes of the same species, for every time 
jfuucus squarrosus was seen in great numbers and the rosettes 
adjoined each other, they were all of the normal size (a diameter 
of about 1 dm.), and the distance from centre to centre is the same 
as the diameter of a rosette (Fig. 1, b). 
Owing to the considerable number and thickness of the blades, 
the bottom and sides of the “ cup ” or “ nest ” are quite impermeable 
to the shoots of other plants. 
In dense colonies of J. squcirrosus there will be very little space 
left for other herbaceous plants. On Crossfell the commonest plant 
accompanying y. squcirrosus was Agrostis vulgaris (A. tenuis 
Sibth. ?), a tender form with narrow leaves. This plant has but 
little ability to resist the pressure of the Juncus, and where the 
latter was growing densely, the Agrostis appeared as thin vertical 
layers, jammed in between the rosettes of the Juncus (Fig. 1, b, c) 
and scarcely overtopping its leaf points. As the jfuucus leaves 
partly keep green and fresh in the winter and do not lose their 
form and firmness after withering, the Agrostis has no chance 
to recover its lost position. In fact, below and between the 
jfuucus rosettes there is a soft mass of withered Agrostis leaves, 
but this plant now produces numerous axillary shoots higher up on 
the stem than usual. It is thus evident that jfuucus squarrosus 
would fail to get air and light enough, were it not able to keep its 
rosette open by means of the rigidly spreading leaves. 
Other species which grow with jf. squarrosus on Crossfell, 
and are caught and suppressed in the same way as Agrostis vulgaris, 
are Desclianipsia flexuosa, Festuca ovina, Galium saxatile, Vaccinium 
1 The anatomical structure is figured in Raunkiaer’s “ De Danske Blom- 
sterplanters Naturalhistorie,” 1, 1895 — 99, p. 407,' fig. 194, D; and Kirchner, 
Loew and Schroeter’s “ Lebensgesch. d. Bliitenpflanzen Mitteleuropas,” 
Lief. 10, 1909, p. 104, fig. 61. 
