176 Pescott, Reproduction of Terrestrial Orchids. [vj"^xxxiv 



NOTES ON THE REPRODUCTION OF TERRESTRIAL 



ORCHIDS. 

 By E. E. Pescott, F.L.S., F.R.H.S. 



{Continued from page 164.) 



{Read before the Field Naturalists' Club of Victoria, Sth Oct., 191 7.) 



Group 3. — Up to the present time I have only been able to 

 place one species of Pterostylis in this group — viz., P. parvi- 

 fiora — although there are species in other genera which exhibit 

 the same mode of reproduction. Tlie habit of growth of this 

 species is as follows : — When the flowering season (March to 

 May) is approaching, the tuber sends up its vegetative growth, 

 culminating in a flowering stem, wliich has no basal foliage. 

 As the flowers approach maturity, tlic flower-stem from the tuber 

 to the ground level thickens considerably, while the repro- 

 ductive tuber for next year's flower develops near the old 

 parent tuber. The fleshy underground portion of the flower- 

 stem develops a vegetative bud, from M'hich a rosette of small 

 foliage appears. Sometimes a second rosette appears, and 

 occasionally a third, all growing from the one stem. According 

 to the strength and size of the tul)er, so is the number of 

 " eyes." This means that an abundant autumn rain in one 

 season, causing the development of a vigorous rosette of 

 foliage, will result in a large tuber full of storage food for the 

 next season ; and in that case, as a result, several buds will 

 develop at the base of the subsequent flower-stems. In 

 succeeding years, two and sojiietimes three flower-stems will 

 have developed from the one growing stem. Later, a juvenile 

 tul)er will appear lower down, on the growth stem. Thus we 

 lind a parent tuber with its reproductive tuber at the base, 

 a juvenile tuber on the stem higher up, and one, two, or three 

 rosettes or flower-stems at ground level. Later, a separate 

 growing stem develops, conveying the sap for other rosettes. 

 In other words, by the lapse of a few years, each rosette comes 

 to have an independent growing stem, all of which are still 

 conjoined, or wrapped up in the original fibrous coating that 

 formed the protective covering or epidermis of the original 

 vegetative stem. And it is only when this fibrous coating 

 decays, in the lapse of years, that each rosette or flower-stem 

 attains an independent existence. 



The Genus Prasophyllum. 



In this genus, with one exception, the lateral roots are 

 produced in the same way, above the parent tuber, but they 

 are usually very stout and very short. Again, terminal ju\-enile 

 tulx'rs are produced on the roots, and these so owrlie the parent 

 tuber that they appear Hke offsets from them. Sometimes 



