Coi.oRADo Weed Seeds 
19 
more, the wall of the ovary is firmly grown to the seed coats. An 
achene (Fig. 7) is a dry, non-splitting, one-seeded fruit resembling 
the caryopsis, but the ovary wall is not firmly grown to the seed- 
coats. A nutlet (Fig. 8) is a small, hard, usually one-seeded 
indehiscent fruit. An utricle (Fig. 9)) is a small, thin-walled, 
bladdery, one-seeded fruit. A true seed is shown in Fig. 11. 
.oi/ter LKt^^umevft 
inner 
■Ci^yleclon 
Fig-. 11. Longitudinal section of a 
true seed (Pumpkin) showing outer and 
inner seed coats (integuments). 
