138 MINNESOTA BOTANICAL STUDIES. 



are unfolded. Their arrangement is spiral from the first, but the 

 divergence is probably not the same as obtains later on. 



The mature rhizomes of both species grow vertically or nearly 

 so in the moist mucky soil of their habitat (Plate XXII, Figs. 3, 5) 

 and not creeping as Dr. Krause states.* 



The large leaves with wide sheathing petioles are closely 

 crow'ded at the crown of the stem with inflorescences borne ap- 

 parently in their axils. At first sight one is therefore inclined to 

 regard these stems as monopodial in structure, but a closer exam- 

 ination reveals their sympodial character. In some of the extra- 

 tropical genera of aroids like Acorus and Calla, where the rhizomes 

 grow more or less horizontally, there is a tendency for them to 

 elongate and the .sympodial nature is more easily recognized. 

 Among these there is also considerable branching. In Syuiplocarpiis 

 and Lysichiton with upright, deeply buried rhizomes the various 

 joints or axes of the sympodium are greatly reduced in length and 

 branching is almost if not entirely confined to the renewal shoot. 

 In both of these genera growth is extremely slow after the plants 

 have reached the flower bearing age. A large number of plants 

 of Symplocarpus have been examined and it has been found that 

 in the latitude of Minneapolis, at least (45° N^.), the yearly in- 

 crease in the length of the stem is only Z-7 mm. Good-sized in- 

 dividuals with rhizomes 20-30 cm. long may range all the way 

 from twenty-five to seventy-five years of age. Perhaps they are 

 even much older, for the rhizomes decay from below as they 

 are gradually pulled down into the soil by the contractile roots 

 (Plate XXII, Fig. 3). Lysichiton usually produces more leaves i>er 

 year than Symplocarpus and consequently adds a little more to its 

 stem yearly. On full grown, vigorous plants of both species, from 

 four to seven axes or joints of the sympodium are added each 

 year. 



* In a recent monograph on the Araceae-Calloideae in Engler".? Pflanzen- 

 i^ich, IV. 23B, page 140, Di'. Kunt Krause of the Berlin Botanical Museum 

 makes a series of absolutely erroneous statements concerning- the m,orphology of 

 Si/mplocarims and Lysichiton. It is true that many of the mistakes trace back 

 to Engler's early investigations on these genera, but as long as the monograph 

 appears under Dr. Krause's name one will lia\e to assume that he concurs in 

 everything he copies from his predecessor and that he .stands sponsor for the 

 statements, whether borrowed or original, contained therein. 



It would seem that when a person undertakes important new monographic 

 work on any group of plants he should invewtigate his nxaterial closely enough 

 to be able to corroborate previous statements of facts, to i-ectify previous errors, 

 and to add reliable new knowledgie to what is already known. Dr. Krause's 

 recent attempt at the Araceae-Calloideae fails signallj' in the.se respects and can 

 but be harmful to a work of such rank as Dos Pflanzenreich. 



