337 
additions received from these countries since the publication of that 
work compose the Kew material of A. pubescens, Engler, as defined 
in the description below. 
Kissner 3185 from German East Africa is a form differing 
slightly from the typical A. pubescens in having shorter, somewhat — 
broader and less acuminate bracts. 
The following then is the nomenclature and classification of 
the specimens of these two species represented in the Kew 
Herbarium :— 
Acanthus arboreus, Forsk. (syn. A. polystachyus, Delile, probably ; 
A, Gaéd, Lindau). 
Abyssinia. Schimper 1534, 1535; Plowden; Steudner 1532, 1533. 
Upper Senaar. Kotschy 489. * 
Acanthus pubescens, Engler (syn. A. arboreus, Forsk., var. 
pubescens, T, Thoms. ; A. ugandensis, C. B. Clarke). 
Uganda. Mahon; Dawe 237; Evan James; Wilson 94; Mason. 
British East Africa. C. F. Elliott 244; Scott Elliott 7057. 
German East Africa. Speke and Grant 136; Kdssner 3185. 
To sum up, the true Acanthus arboreus, Forsk., if identical with 
A. polystachyus, Delile, is a plant of Arabia, Abyssinia, and 
Somaliland, while A. pubescens, Engler, has a more southern range, 
being common in Uganda and having been several times collected 
in British and German East Africa. 
There is one point which owing to the lack of material has not 
been completely cleared up. In Trans. Linn. Soc., vol. xxix., 
p. 129, there is under Acanthus arboreus, Forsk., var. pubescens, a 
note by Col. Grant to the effect that the seeds of this plant are 
“covered with a down which makes the fingers itch.” Speke and 
Grant’s specimen at Kew contains no seed. owever, in a capsule 
mounted on the same sheet as the specimen collected by Miss Mason 
in Uganda is a single seed and this is completely covered with sti 
brown hairs which, like the well-known hairs on the fruits of species 
of Mucuna, come off easily on to the hands when rubbed and in 
any quantity would no doubt cause a noticeable irritation. Hence 
it seems that there is here another, probably constant, character for 
distinguishing A. pubescens from A. arboreus for the seeds of the 
latter are flat, smooth, and shining. 
Acanthus pubescens, Hngler, Hochgebirgs Fl. Trop. Afr. (1892), 
p. 390 (Acanthaceae-Acanthoideae) ; descriptionem ampliatam 
confecit, W. B. Turrill; A. arboreo, Forsk., affinis, sed bracteis 
minoribus, sepalis lateralibus latis saepissime obtusis marginibus 
molliter ciliatis praecipue differt. : 
Planta erecta, 1-3 m. alta, caulibus subquadrangularibus glabris 
vel plus minusve pubescentibus. Folia ambitu elliptico-lanceolata, 
apice acuta spinescentia, basi cordata vel rotundata, usque ad 20 cm. 
longa, 9 cm. lata, subcoriacea, glabra vel plus minusve pubescentia, 
irregulariter lobata, lobis spinescentibus, nervis secondariis utrinque 
usque ad 14 pagina utraque conspicuis, petiolis 1-2 cm. longis. 
Spicae multiflorae ; bracteae ovatae, apice acutae vel acuminatae 
usque ad 2 mm. longae, 1°5 mm. latae, pagina utraque dense puber- 
ulae, marginibus spinescentes ; bracteolae lineari-lanceolatae, apice 
acuminatae, 1°5 cm. longae, 2-3 mm. latae, pagina utraque puberulae, 
32221 B 2 
