﻿APRIL 1 TO JUNE 30, 1016. 61 



42765. Engelhardtia aceriflora (Eeinw.) Blume. Juglandacese. 



From Nice, France. Seeds presented by Dr. A. Robertson Proschowsky. 

 Received May 16, 1916. 



A very tall tree, with compound leaves somewhat like those of the walnut, 

 and inconspicuous flowers disposed in drooping, spicate panicles. These are 

 succeeded by little fruits which are about the size of a pea, each seated on the 

 base of a three-lobed, beautifully veined and colored bract. These are often 

 more than a foot long and hang very gracefully among the foliage. (Adapted 

 from Lindley, Treasury of Botany, pt. 1, p. 451.) 



42786. Rubus ulmifolius bellidiflorus (Koch) Focke. Rosacea. 



Bramble. 



From Amsterdam, Netherlands. Presented by the director, Botanic Garden, 

 University of Amsterdam. Received May 15, 1916. 



A very handsome, double-flowered pink bramble, commonly used for planting 

 in England. Each flower produces an extraordinary number of narrow petals, 

 making a gay display in July and August. This bramble is highly recommended 

 for half -shady woodlands. 



42767. Pavetta zimmermanniana Valet. Rubiacese. 



From Buitenzorg, Java. Seeds presented by Dr. J. C. Koningsberger, 

 director, Botanic Gardens. Received May 12, 1916. 



A small rubiaceous tree or shrub, with opposite, nearly elliptic leaves and 

 clusters of small, slender-tubed white flowers. 



"The remarkable researches of Zimmerman and Faber (detailed in the 

 Jahrbiicher fur Wissenschaftliche Botanik, vol. 51, p. 285, 1912, and vol. 54, 

 p. 243, 1914) make this species of unusual interest. Faber has proved that 

 the leaves of this and of several other species of Pavetta, Psychotria, and 

 possibly other genera of the Rubiacese contain colonies Of a nonmotile, nitrogen- 

 fixing bacterium which he names Myco-oacterium rubiacearum. The bacteria 

 of this genus almost invariably inhabit the micropyle of the young seed, and, 

 when the seed germinates, grow through certain stomata of the very young 

 leaves and into the intracellular spaces formed in the leaf tissues around these 

 stomata. Cavities are formed through the growth of the epidermal cells which 

 later close entirely and make bacterial nodules which are deeply imbedded in 

 the leaf tissues. A single leaf may have several dozen of these symbiotic bac- 

 terial nodules. Faber was able, by treating the seeds with hot water and a 

 sublimate solution, to kill the inhabiting myco-bac-teria and, later, to infect 

 part of the seedlings grown from these seeds with pure cultures of the bac- 

 terium. The artificially infected seedlings grown in soil free from combined 

 nitrogen grew well and remained healthy for four months, whereas* those not 

 so infected turned yellowish white and died in three or four weeks. The plants 

 from unsterilized seeds produced leaves bearing many more bacterial nodules 

 than did those from sterilized seeds which were later artificially inoculated. 

 In view of the facts that these rubiaceous plants with bacterial nodule-bearing 

 leaves occur in many parts of the Tropics and that in India, at least, the value 

 of their leaves for manure has long been recognized, and considering the 

 value of nitrogen-fixing legumes as fertilizers, the suggestion of Faber that 

 we may have in these tropical trees and shrubs plants of positive agricultural 

 value for the tropical planter is well worthy of consideration. The value of 



