POLYGONACES, 53 
APETALA. 
PotyconacE® (Dock FamIty). 
A small but widely spread order, including a few economic species, 
Rheum (Rhubarb), Polygonum Fagopyrum, L, (Buckwheat), but no poison- 
ous ones, and a few troublesome weeds (Docks, &c.). The leaves of many, 
species are more or less acid, and the stems and roots usually bitter. Hence 
the plants are useless as fodder or grazing plants. Usually herbs, with 
sheathing stipules at the knots on the stem; flowers small and clustered ; 
perianth, four to six partite, enclosing the seed-like, usually triangular, nut. 
Flowers usually small, perianth simple or apparently simple, or none. 
Rumex crispus, L., R. conglomeratus, L., and R. obtusifolius, L., are 
the commoner Docks, and all have a fruiting perianth of six segments, the 
three inner ones enlarged. Nativesof Europe and Asia. These tall perennial 
weeds are not easily got rid of, especially on undrained and on pasture 
land. The seeds are not carried any distance by the wind, although the 
one-seeded fruits are more or less winged in some species, but are usually 
introduced with impure clover or grass seed. They flower readily, and 
produce an abundance of seed, which may lie dormant a few years in the 
soil. Any part of the long tap root, when cut, may form buds, and thus 
new plants. : 
Hence, for eradication the ground must be ploughed, harrowed, horse- 
raked, the pieces of root collected after each operation, piled in heaps or 
pits, covered with quicklime, and next year used as manure, if all are dead. 
The land must be kept under good tillage and root crops until clean. Great 
care should be taken when sowing down again to use only pure grass and 
clover seed. The triangular brown shining seeds of the ordinary dock are 
easily recognized. 
Young Dock leaves can be used ‘as a coarse kind of Spinach, but the 
fodder value of the plant is practically ‘‘nil.’?’ Darwin (A Naturalist’s 
Voyage round the World, p. 513), noted in 1835 that ‘‘ the common Dock 
is also widely disseminated (in New Zealand), and will, I fear, for ever 
remain a proof of the rascality of. an Englishman who sold the seeds for 
those of the Tobacco plant.’’ 
R. Acetosella, L., the Sheep’s Sorrel, and &. Acetosa, L., the Sorrel, 
are. both small annuals from Europe and Asia, with bright green acid 
leaves often turning red when older. The former was established as far 
back as 1802, and likes dry open places, but the latter, which prefers 
moist pastures, has not as yet been recorded. The young leaves have been 
used as a vegetable, but their acidity, due to the presence of acid oxalate 
of potassium, renders them unsuitable for this purpose or as fodder plants. 
These plants seed freely, and can only be kept under by good cultivation 
when once allowed to develop and flower unchecked and in abundance. 
They thrive less in well-opened, aerated, and limed soil, and are kept down 
by the larger grasses and clovers. 
Polygonum. In this genus the flowers have a perianth of five segments. 
P. aviculare L., Knot Weed, Knot Grass, or Hog Weed is a small, 
wiry annual prostrate on open ground, but erect and a foot or so high when 
growing among other vegetation. Its small white-tipped flowers are clus- 
tered in the axils of the leaves, which have a white membrane sheathing 
the stem at their bases. The triangular seeds are not shiny, but extremely 
minutely roughened. They form a common impurity among agricultural 
seed, and it was in this way that the plant was originally introduced. to 
Victoria. The plant is now spread over nearly the whole world. The 
‘seed lasts for some time in the soil, and soon ripens on the plant. Hence, 
