PALEOBOTANY- — BERRY. 309 



Gleichenias all grow in thickets; the foliage is coriaceous and 

 perennial and the growth indeterminate. The fronds branch dichot- 

 omously and resume growth season after season, so that in some 

 cases the fronds are said to be over 100 feet in length. The pinnae 

 are pinnatilied with small ovate segments or elongate pectinate pin- 

 nules. Primitive foliar characters are the dichotomous habit and 

 the frequent development of subsidiary pinnae between the normal 

 ones. Sori snbglobose, comprising two to six nearly sessile sporangia, 

 found on the back of a vein. Each sporangium is surrounded by 

 a broad, transverse equatorial annnliis and opens vertically. Spores 

 are ovoid or tetrahedral, without chlorophyll and with a single dorsal 

 line. 



The existing species range from China and Japan to New Zealand, 

 Tasmania, and South Africa in the Eastern, and from Louisiana to 

 the Straits of Magellan and the Falkland Islands in the Western 

 Hemisphere. While largely tropical, temperature is apparently not 

 an important factor, since they occur at high elevations in the Andes 

 and elsewhere, and range southward to the bleak country of the 

 Straits of Magellan. Moisture seems to be the most 

 important factor, for while the foliage is more or 

 less xerophytic, they do not grow outside regions 

 of abundant rainfall or great humidity. They are 

 common throughout Oceania, being especially 

 abundant in the Hawaiian Islands. Their pres- 

 ent distribution is clearly indicative of a geological 'J^^J^^ 

 history, and fortunately considerable of this history upper Triassic of 



i npi _e -i • i i.i it i Switzerland. X5. 



is known, the family is evidently an old one and 

 appears to be present as early as the Carboniferous in the genus Oli- 

 gocarpia, which had sphenopteroid foliage and circular sori consist- 

 ing of from six to ten pyriform sporangia with a complete transverse 

 annulus (Zeiller 1888, vide Scott, 1908). The Carboniferous genus 

 Gleichenitcs Goppert and the dichotomius branching genera Mari- 

 opteris Zeiller and Diplothmema Stur are all now considered as 

 probable Pteridospermophytes and it is evident that the Gleichenoid 

 habit of growth was common in both Paleozoic and Mesozoic, and is 

 without special bearing on botanical relationship. 



The family is not known to have been abundant in the Triassic or 

 Jurassic, the Keuper genus Mertensides of Fontaine being often 

 referred to the Marattiales. A species of Gleichenia with well- 

 marked fructications is, however, recorded from the Keuper of 

 Switzerland and the genus is known from the Rhaetian of Fran- 

 conia. Jurassic species are recorded from California, India, Italy, 

 and Poland. Throughout the Cretaceous Gleichenia becomes almost 

 world-wide in its distribution. While the number of species has 



1366.30°— 2U 21 



