io 6 
THE SEED 
Plantago, Collomia, Brassica, &c.; sometimes there are scales or hairs 
upon it and these swell, as in many Acanthaceae. This is usually 
regarded as a mechanism for attaching the seed to favourable spots for 
germination. The testa is usually marked with a scar, the hilum , where 
the stalk separated from the seed. 
Many seeds are covered by an extra coat (aril) that is developed 
like the original integuments, i.e. by a cup-like growth of tissue around 
the seed from the top of the stalk or rarely from the micropyle. Its 
development may be studied in fruits of Euonymus. Arillate seeds 
occur in Taxus, many Commelinaceae, &c., Dilleniaceae, Celastraceae, 
Sapindaceae, Passiflora, Nymphaeaceae, Myristica, &c. In Euphor- 
biaceae, &c. the aril remains small and hard and is called a caruncle , 
but usually it is fleshy. 
The seed may be albuminous or exalbuminous (above), in the former 
case with endosperm or perisperm or both ; the endosperm may be 
starchy , farinaceous , floury , or mealy (the cells containing starch and 
when powdered forming a floury dust) as in Triticum, oily as in 
Papaver, Ricinus, See., fleshy as in Berberis, horny as in Coffea, bony 
as in Phoenix and Phytelephas, ruminate (marked by wavy transverse 
lines which give it a marbled look) as in Anonaceae, mucilaginous , &c. 
The embryo (rarely embryos) may be straight, curved, twisted, &c. 
(and cf Cruciferae). It may have one, two, or several cotyledons (this 
is an important point in classification), or rarely none, as in Cuscuta, &c. 
Mention must be made, lastly, of the adventitious embryos of 
Funkia, Nothoscordum, Alchornea, &c. and of the peculiar cases of 
Ginkgo, and Gnetum, where the seed c ripens ’ before fertilisation ; see 
Part II. 
The Fruit. The ovule is usually enclosed in an ovary, 
or protected by scales as in Coniferae, and these parts are 
stimulated to further growth by the act of fertilisation, and 
develope together with the ripening seed, finally forming a 
covering or protection to it, known as the fruit . The fruit 
may be defined as ‘the product of that process of growth 
which is initiated by the act of fertilisation.’ This of course 
includes the seed, and in Cycas, Taxus, &c. fruit and seed 
are the same. Usually, however, the seed is enclosed in an 
envelope or pericarp , developed from the gynceceum, &c. 
Many writers lay stress on the difference between true fruits 
and false fruits (pseudo carp s'), the former being defined as 
the product of the ovary only, the latter as the product of 
the ovary together with any other organ that developes, such 
as the axis (as in apple or rose) or perianth. The terms, 
however, are inconsistently used, and are better avoided. 
Other changes often occur in the change of an ovary to 
a fruit ; a very common one is the suppression of some (or 
