528 



BOTANY 



other forms have developed. Sometimes by the suppression of one whorl, either 



the epipetalous or the episepalous, the number of stamens is reduced to five, or, in 



other instances, one whorl is re- 

 presented by staminodia. In 

 most cases, however, the number 

 of stamens is indefinite in con- 

 sequence of a division of the 

 staminal rudiments extending to 

 their very base, the stamens being 

 grouped correspondingly in either 

 five or ten bundles. In some 

 forms they are united at the 

 base, just as in the Malvaceae, 

 but the andrcecia of the Tiliaceae 

 are always distinguishable by 

 their dithecious, introrse anthers 

 and smoother pollen-grains. The 

 stamens in some species, again, 

 are in part transformed into 

 petaloid staminodia {e.g. Tilia 

 tmnentosa). 



This family, which is chiefly 

 tropical, is represented in 

 northern regions only by the 

 genus Tilia, variously known 

 under the name of Linden, Bass- 

 wood, or Lime-tree. Lime-trees 

 have two-ranked leaves with small 

 stipules, and flowers aggregated 

 in a cymose umbel. The slender 

 stalk of each inflorescence is 

 adnate to an elongated hypso- 

 pliyll, differing from the foliage- 

 leaves (Fig. 493) both in its yellowish colour and shape. The numerous 



stamens are developed from five episepalous rudiments, and in older flowers are 



distinctly grouped in five bundles. The ovary is hairy, contains two ovules in 



each of the five loculi, and ripens into an indehiscent 



fruit with a single endospermous seed. Tilia parvifolia 



has five- to nine-flowered inflorescences and heart-shaped 



leaves, which are beset on the under side, in the angles 



of the nerves, with brown rafts of hair, but otherwise 



are glabrous ; the large-leafed Linden, T. grandifolia 



{T. platyphyllos), has leaves, hairy on the under surface, 



and three- to five -flowered inflorescences. The flowers 



of T. tomentosa have five white staminodia resembling 



the petals. 



* Officinal.— Both Tilia parvifolia and grandifolia, 



yielding Flob.es Tiliae. 



Family Sterculiaceae. — Flowers often apetalous ; calyx gamosepalous 



contorted ; stamens usually not very numerous, monadelphous ; anthers 



exteorse, dithecious ; pollen-grains not often spiny (Figs. 494-496). 



Fig. 403. — Tilia parvifolia. A, Inflorescence (a), with 

 hypsophyll o (nat. size). B, Longitudinal section of 

 fruit (magnified); o, pericarp; p, atrophied dissepi- 

 ment and ovule ; q, seed ; r, endosperm ; s, embryo ; t, 

 its radicle. — Officinal. (After Berg and Schmidt.) 



Fig. 494. - 

 Floral 

 broma). 



-Sterculiaceae. 

 diagram (Tlieo- 

 (After Bicblee.) 



