92 MISSOURI BOTANICAL GARDEN. 
There are three types of Yucca fruits which illustrate 
three distinct methods of dissemination. These types of 
fruits were used by Dr. Engelmann to distinguish the three 
groups of the true Yuccas. 
Sarcoyucca: — Fruits pendent, fleshy, indehiscent; 
seeds thick and wingless, with ruminated endo- 
sperm. 
Clistoyucca: — Fruits pendent, dry and coriaceous, 
indehiscent; seeds thinner than in Sarcoyucca, wing- 
less; endosperm entire. 
Chaenoyucca :— Fruits erect, capsular with septicidal 
dehiscence; seeds strongly compressed and thin 
with a winged margin; endosperm entire. 
The Sarcoyuccas, comprising nearly one-half of the 
known species of Yucca, have sweet edible fruits and are 
apparently well adapted for dissemination by fruit-eating 
animals, especially birds. In this group the seeds are 
usually protected by the inner part of the ovarian wall, 
which in the development of the fruit becomes hard and 
firm, suggesting in texture and functions the core of an 
apple. The pulp is easily removed from the core, which is 
more or less shaped to the seeds. This structure would 
suggest that the pulp only is eaten, the core and seeds 
being thrown away. In this case, the fruits, it would 
seem, were intended to be carried away by the animals 
eating them in order to remove the seeds from the parent 
plant. Birds in picking away the tender pulp would 
hardly reach the protected seeds but merely remove the 
pulp, leaving the core and seeds. This would not serve the 
function desired. Certain species of the Sarcoyuccas, 
baccata, valida, and G'uatemalensis, having the papery core, 
are said by Dr. Trelease f to fall early. It is quite prob- 
able that this is a habit developed to aid in their dissemi- 
* Trelease, Wm., ‘‘Notes and Observations. 7. Yucca Guatemalensis 
Baker.’’? Mo, Botanical Garden, 5th Annual Report (St. Louis, 1894), p. 
166. 
