TypHa Insects: THEIR EcoLoGicAL RELATIONSHIPS 467 
TABLE 1. Computation or THE AVERAGE NUMBER OF SEEDS IN Eacu TypHa Heap 
Sample Sample Sample Sample 
1 2 3 d 
Length of head (millimeters)...... 160 180 180 160 
Weight of entire head (grams)..... 35.6735 30.5632 35.2700 27.1150 
Weight of rachis (grams)......... 2.8330 1.9480 2.1610 1.6850 
- Weight of seeds minus rachis 
PERINS) PPMP Cre. oc ose se: 32.8405 28.6152 33.1090 25.4300 
Weight of detached bunch of seeds 
(Grams) eer etelac nese: 0.0179 0.0490 0.0400 0.0400 
Number of seeds in detached bunch. 167 480 300 295 
Estimated total number of seeds 
on ihaxibe 55.508 306, 393 280,320 248,317 187,546 
Average number for the four heads, 255,644. 
GERMINATION OF TYPHA LATIFOLIA 
The manner of germination of T'ypha latifolia is very unusual. The 
development of the plant from the seed was observed in the laboratory. 
The seeds were placed in watch glasses and could thus be studied under 
the binocular microscope from day to day. Some of the watch glasses 
contained only water in which the seeds germinated, while in others a 
little soil was placed in the bottom in order to observe the growth of the 
roots. The watch glasses were kept covered to prevent evaporation. 
The seeds, when first thrown upon the surface of the water, remained 
floating. Soon, however, the pericarp broke open and the little seeds 
sank to the bottom. 
The seeds are much elongated, pointed at one end and at the other 
closed by a cone-shaped trapdoor, or cap (Plate XX XIX, 3). The general 
appearance of the seed is not much unlike some of the insect eggs which 
are closed at one end with a capsule-like cover. Ten seeds of T. latifolia, 
chosen at random from two heads, were removed from the pericarp and 
the length and diameter of each was carefully measured (table 2). The 
average length of the seed was found to be 1.339 millimeters, and the 
average greatest diameter, 0.307 millimeter. The surface of the seed is 
sculptured with small, branching ridges, starting at the end of the cap and 
branching as they run down to the other end. The entire seed, including 
both its pericarp and its pappus, is about 10 to 12 millimeters long. 
The pappus consists of from 15 to 20 white hairs, attached to the base 
and lower quarter of the stalk (Plate XX XIX, | and 2). 
