542 The Horsebeans 



is about 0.69. It takes a fine polish, is very durable, and used for fence-posts and 

 in general construction. The seeds were used by the early pioneers of Kentucky as 

 a substitute for coffee. It is often planted for ornament and shade, on account of 

 its rapid growth, graceful foliage, and odd winter aspect. 



The generic name is Greek, referring to its stout, naked branches. There is 

 but one other species, Gymnocladus chinensis Baillon, a native of southern China; 

 the American species is the type of the genus. Fossil remains referable to the genus 

 have been found in the Tertiary formations of Europe. 



V. THE HORSEBEANS 



GENUS PARKENSONIA [PLUMIER] LINN^US 



^jARKINSONIA consists of but 3 species of thin-barked, spiny trees or 

 shrubs of the warmer parts of America and Africa; the Horsebean, 

 Parhinsonia aculeaia Lumaeus, has become naturalized throughout the 

 tropics, having been grown and used as a hedge and fodder plant for 

 a long time. 



The leaves are alternate or clustered, on short leaf-stalks, which fork into 2 

 to 4 rachises bearing numerous pairs of small sessile leaflets. The flowers are 

 perfect, nearly regular, axillary, racemose, the pedicels jointed; calyx short, bell- 

 shaped, the 5 lobes nearly equal, reflexed; corolla of 5 yellow spreading petals, 

 much longer than the cal)^-lobes, the upper or standard broadest and clawed ; sta- 

 mens 10, in two series, their filaments distinct, hairy below, the anthers opening 

 lengthwise; ovary borne at the base of the calyx-tube, short-stalked, hairy, many- 

 ovuled, the style slender. The fruit is a linear legume, tapering at both ends, 

 nearly circular in cross-section, constricted between the distant seeds, longitudinally 

 veined, 2-valved and leathery; seeds few, longitudinally placed, brown and hard^ 

 the endosperm homy. 



The type species is Parkinsonia aculeata. The name is in commemoration of 

 John Parkinson, an English botanist, herbahst to James I, who died in 1750. 

 Our species are : 



Racemes elongated; leaflets 20 to 30 pairs. i. -P. aculeata. 



Racemes short; leaflets 4 to 6 pairs. 2. P. microphyUa. 



I. HORSEBEAN — ParMnsonia acnleata Linnaeus 



This graceful and striking little tree or shrub, also called Retama, is supposed 

 to be native from the Rio Grande in Texas, southward into Mexico. It is well 

 established and naturalized in all warm and tropical regions and occurs in our area 

 from Florida to the Pacific coast. It attains a maximum height of about 9 meters, 

 with a trunk diameter of 3 dm. 



The short trunk divides into spreading or drooping branches. The reddish 



