April, 1921. 



The Canadian Field-Naturalist. 



75 



parent transitions to Angiosperms. It 

 bears cones like gymnosperms but in tlie 

 axil of each scale is a flower of Anj^io- 

 speraiic structure. Its distribution is no 

 less remarkable than its morphology. In 

 this locality it is found in an^ area of oidy 

 a few square miles. This and another 

 similar locality further nortji are the only 

 places in the world where it is found. 



Tunihoa's neighbors have adopted var- 

 ied methods of contending with the 

 drought. The Naras, Acanthosicyos hor- 

 rida (Cucurbitaceae), has completely dis- 

 carded its leaves and consists simply of a 

 mass of green, hard, extremely sjiarp 

 pointed thorns sprawling over the sand. 

 Its roots go down to subterranean water 

 and may be fifteen meters long. The Ge- 

 raniaceous Sarcocaulon has completely wa- 

 terproofed itself in a coat of hard wax 

 which may be ten millimeters thick. The 

 coat remains as a hollow shell long after 

 the plant has died and rotted away. The 

 wax burns readily and the plant is there- 

 fore called Hottentot candle. Several spe- 

 cies Jriave imitated the succulent cactus 

 though belonging to very different fam- 

 ilies. Several members of the milkweed 

 family have become switch plants. Strang- 

 est of all perhaps in this climate is the 

 ice-plant (Mesembryanthemum) with its 

 large soft leaves completely covered by 

 droplets of cool liquid. To expose its wa- 

 ter in this way when the supply is so 

 extremely scanty seems to be about the 

 worst thing the plant could do. 



A fact whicj^i soon strikes the botanist 

 is that in spite of strong resemblances in 

 external features to the plants of Amer- 

 ican deserts these belong to very different 

 families. For example, one sees many cac- 

 tus-like plants but no cacti. A large pro- 

 portion of the flora consists of members 

 of the milkweed family which are there 

 switch-plants. Families which the North 

 American botanist has never seen there 

 simulate our own xerophytes to a remark- 

 able degree. So strong is ijcie resemblance 

 in many cases that one can scarcely believe 

 that the flowers, showing the true botani- 

 cal relationship, really belong to the plants 

 on which they are found. We ihave here 

 a good illustration of entirely unrelated 

 plants acquiring the same characteristics 

 iinder similar conditions. 



During the w;iole trip only one species 

 of our great rose family was seen, only 

 three crucifers and only three members 

 of the buttercup family (all Clematis). 

 On the other hand, families poorly repre- 

 sented here but relatively abundant there 

 are the Asclepiadaceae, Tiliaceae (chiefly 

 shrubby Grewias), Geraniaceae, Aizoaceae, 

 Zygophyllaceae and Anacardiaceae. Fam- 

 ilies with many representatives in both 

 places are Liliaceae, Leguminosae and Com- 

 positae. 



The old river beds constitute an inter- 

 esting variation from the desert waste. 

 Their periodic flooding from the interior 

 enables a richer though still sparse vegeta- 

 tion to survive. An occasional gardener 

 takes advantage of this moisture to raise 

 a few vegetables which are sold at fabulous 

 prices to the town dwellers. A number of 

 large wells as big as a house are dug in 

 the dry river bottom. Into these a little 

 water soaks during the night and is pump- 

 ed out next day on to the small garden. 

 After a time tjhe wells go completely dry 

 and the gardener moves a half-mile along 

 the river and digs a new set. Sometimes 

 several moves are made between floodings. 



In these river bottoms the vegetation 

 consists chiefly of scattered shrubs and 

 trees. There are the date palm, a fig, 

 several thorny acacias, the tamarisk and 

 an ebony. One of the most successful 

 plants in this habitat is a tobacco {Nico- 

 tiana glauca) whicjli reaches the size of a 

 'Small tree. It was introduced by the early 

 missionaries. 



Farther inland the increased moisture 

 supports a somewhat richer vegetation. In 

 places tlie vegetation is of a type which 

 rapidly bursts into flower after a rain and 

 then dries up until the next rain. In few 

 places is the ground completely covered, 

 the plants being in scattered clumps and 

 consisting chiefly of grasses. The German 

 Government had encouraged in every pos- 

 sible way the agricultural development of 

 tjie colony, but even the best parts of the 

 country are unsuited to anything but ran- 

 ching. The few ranchers who had been 

 induced to .settle in the eastern portion 

 were making a precarious livelihood at the 

 beginning of the war. A few municipal- 

 ities in Canada are worth more agricultur- 

 ally than the whole territory. 



