BEHAVIOR OF ASPARAGUS PLUMOSUS TOWARD 

 GRAVITATION AND LIGHT' 



L. LENORE CONOVER 



University of Michigan 



Asparagus plumosus (Baker), var. nanus, a common green- 

 house plant, has a short horizontal rhizome which sends down- 

 ward and outward a mass of thick, fleshy roots, and sends upward 

 shoot after shoot, which develop into aerial plumes of most 

 delicate and decorative structure. Like the members of the 

 Asparagus genus generally, this one produces no assimilating 

 leaves, but substitutes for leaves clusters of minute, needle-like, 

 dwarf branches. The plant is commonly propagated from seed. 

 The first shoot to appear above ground from the seed, rises ver- 

 tically to a height of 5 to 10 cm. and then the tip makes a char- 

 acteristic bend to the horizontal position. Growth produces 

 a horizontal portion of a few centimeters, lateral branches develop 

 from the horizontal axis, and secondary and tertiary branches 

 appear, those of the last order being clusters of fine needles 5 

 to 7 mm. in length. When the upper part of the main axis of 

 the aerial shoot and its branches have attained their final devel- 

 opment, the entire system Hes in a horizontal plane and presents 

 the appearance of having come from a plant-press. 



As the plant becomes older new shoots rise from the rhizome, 

 each shoot successively rising higher than its predecessor, and 

 each one bending its tip to the horizontal before the assimilat- 

 ing branches are unfolded. The increase in height of the succes- 

 sive shoots is controlled to a considerable extent by the amount 

 of space given to the roots. Confinement to a small pot will 

 keep the shoots below 30 cm. for years; whereas' optimum con- 

 ditions of growth will turn the plant after the lapse of several 



'Contribution 134 from the Botanical Department of the Universitj- of Mich- 

 igan. 



61 



THE PLANT WORLD, VOL. 16, NO. 2, FEBRU.IRY, 1913 



