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pearance, though not so fleshy. Under the conditions to which 
it has been subjected, the plant assumes the look of one belonging 
to another genus of the same family, but of a different habit, 
since the stone-crops are frequenters of rocks and dry places. 
This may show a common origin in which the ancestor of 
Penthorum resembled Sedum more closely than at present. 
The behavior of these subterranean stems in water may also 
throw some light on the true place of Penthorum in the natural 
system, since it has been a matter of dispute. Penthorum and 
Diamorpha forming the group Diamorphee, and usually in- 
cluded with Crassulacez, are placed by some with the Saxifra- 
gacez. La Maout and Decaisne metion them in this connection, 
plainly regarding them as more closely allied to the latter than 
to Crassulacez, ‘‘ whose relationship they evidently reject by their 
several-celled ovary.” Schénland, who prepared the article 
“Crassulacee” for Engler and Prantl’s Pflanzenfamilien, makes 
a group of Penthorum, Diamorpha and Triactina, and places 
them in his arrangement nearest to Saxifragacez. They are 
thought to be more nearly related to Sedum than to other genera 
of the order, or pointing to Sedum for their parentage. The 
small, crowded and somewhat thickened leaves borne by these 
spreading subterranean shoots, or stolons, of Pexthorum, (since 
they also start from the stem above ground and form true 
stolons), make this relationship still more apparent, and help to 
remove one objection to placing it with the Crassulaceze. Schén- 
land writes as follows with regard to this relationship: “ The 
Crassulacez constitute a very natural group of forms. The only 
genus that has been separated from them by Feonnit authors is 
Penthorum, which Baillon has placed with the Saxifragacez. Its 
Possession of membranaceous and not fleshy leaves cannot be al- 
leged as the sole ground for this, since many species of Crassula, 
Vialanchoe, etc., also have quite thin, but slightly thickened 
leaves. Hence it may be recommended to leave Penthorum 
here” (with the Crassulacez.)* . E. J. HI. 
ENGLEWoop, CHICAGO, ILL., Sept. 6, 1892. ee 
*Die Natiirlichen Pflanzenfamilien, 111 Teil, 2 Abt. a., P- 
