248 
THE DICTIONARY OF GARDENING, 
Ptychosperma—continued. 
apet, lft. to 14ft. long, dark green; petioles broadly sheathing 
at the base. Stem somewhat stout, straight. k. about 60ft. 
Queensland and New South Wales. A very elegant species, and 
a most useful conservatory or cool greenhouse plant. See 
. 317. SYNS. Archontopheniz Cunninghamiana (this name is 
the correct one), Seaforthia elegans (B. M. 4961). 
P. Kuhlii (Kuhl’s). A synonym of Pinanga Kuhlii. 
P. Macarthurii (MacArthur’s). l. pinnate; leaflets arching, 
linear-oblon 3 
— 4in. 8in. long. New Guinea, 1879. 
inct palm, SYN. Kentia Macarthurii. 
P. Normanbyi arent a ., inflorescence ovoid, axillary. 
fr. ovoid, with a conical tip, about lin. long. l. 8ft. to 10ft. 
long. h. 40ft. to 60ft. Australia, SyNns. Areca Normanbyi, Cocos 
Normanbyi. 
P. Rumphii (Rumph’s). A synonym of Drymophloeus olive- 
Sormis. 
P. rupicola (rock-loving). A synonym of L rupicol 
P. Seemanii ——— l. pinnate ; pinne erose-dentate, some- 
what resembl — of a Caryota in appearance, and of a bright 
green colour, Si when fully developed, about lin, in diameter, 
strong. Fiji Islands, 1879. An elegant, dwarf-growing species. 
PUBERULOUS. Minutely pubescent. 
PUBESCENT. Softly downy or hairy, 
PUCCINIA (named after an Italian botanist, 
Puccini). A large genus of parasitic Fungi belonging to 
the order Uredinew. In this order, the Fungi grow, with 
a doubtful exception or two, on living plants, into which 
they push their jointed mycelium. The reproduction is 
always effected by conidia, or spores, produced on 
branches from the mycelium, and never inclosed in 
larger cells, as in Mould or in Pyrenomycetes 
(which see). The conidia are usually crowded together 
in masses, which, for a time, are protected by the 
epidermis of the host-plant; but this generally becomes 
torn, and the conidia are exposed. The conidia are 
known to be of two, or even more, forms in almost all 
the species in the order, and these forms are usually 
very different from one another, affording very striking 
examples of the phenomenon called “pleomorphism.” So 
different are they, that several genera were established 
on what are now known to be only forms of the same 
Fungi as had already received names under other 
forms; hence, much confusion has arisen, and this is 
only gradually being overcome by careful and exact 
observations. Even yet much doubt exists as to the 
true relationships of many of the species. An attempt 
will be made to render this part of the subject more 
clear by describing what is now generally accepted 
as the life-history of two or three of the more important 
species of the genus Puccinia. The various forms of 
conidia alternate with one another in the cycle of 
An elegant and 
development of each species, and experiments have led- 
to the belief that some species of Puccinia live on 
different host-plants in the different stages of the cycle. 
truncate or oblique, and unequally toothed at | 
The forms of reproductive organs met with in the | 
most complete cycles in the genus, , that believed to 
exist in P. graminis, are three or four in number. The 
names employed to denote them were formerly given to 
them when they were regarded as different species, 
belonging to genera distinct from that now recognised 
as the more mature condition (viz., Puccinia). The 
forms are as follows: 
1. The Æcidium (old generic name), or Cluster-cup, in 
the form of a cup, at first closed, afterwards open above. 
The sides of the cup (peridium) consist of a single 
layer of cells. The hollow is filled with closely-packed, 
erect branches, arising from the mycelium, each of which 
bears a chain or row of rounded, or angular, thin- 
walled, yellow cells, which separate from one another, 
and „germinate readily, pushing out a mycelium thread. 
On a leaf of the host-plant, the mycelium pushes through 
a stoma, and produces the Fungus anew. The Cluster- 
cups usually stand, as the name denotes, in clusters, on 
thickened, discoloured tissues of the hosts, though, occa- 
Puccinia—continued. 
sionally, they are scattered over the green parts without 
causing much discoloration. ‘They generally stand on 
young stems and on the lower surface of leaves (see 
* 
FIG. 318. LEAVES OF BERBERIS VULGARIS COVERED WITH ÆCIDIUM * 
BERBERIDIS (believed to be a stage in the development of 
Puccinia graminis)—a, Aicidium-patch on Leaf. 
Fig. 318), but may be on the upper surface also. On 
the same mass of tissue as the cups, but, in general, on 
the other side of the leaf, small, flask-shaped spaces 
Fic. 319. TRANSVERSE SECTION OF LEAF OF BERBERIS VULGARIS, — 
sho Spermogonia and Æcidium Berberidis, magnified con- 
siderably—a, Aicidium mm’ Bis ned; b, Thickened Tissue 
of Leaf; c, c, Aicidium ully opened, with Spores r 
dropping out; e, e, Skin of Leaf; A, h, Outer Coat of Æci- a 
dium Cups ; sp, Spermogonia, 7 
(spermogonia) open by narrow mouths (see Fig. 319). — 
They are lined with branches of mycelium, bearing 
extremely small, rod-like bodies (spermatia), which do 
not seem to act as spores, and whose use to the Fungus 
is doubtful. 3 " 
2. The Uredo (old generic name), is often developed 
on the same mycelium as the former, but later; it 
may grow only on a different host-plant. The uredo- 
spores are not inclosed in a cup, or peridinm, but are 
formed on the surface of convex masses of mycelium. | 
These masses are usually covered and protected by the 
epidermis of the host-plant till the sp are ripe, W 
the epidermis bursts. The spores are produced singly 
on erect branches (see Fig. 320), and, when’ ripe, 
fall off, and then are hardly to be distinguished from 
