185 
Life-history. It is a so-called lepto-form or Leptopuccinia, i.e. it 
has neither aecia nor uredinia, producing only telia. The teliospores 
usually germinate 1m situ, as soon as mature, to form promycelia with 
sporidia. 
The Primary Cycles occur on the first leaves developed from the 
perennial root in the spring. The sources of inoculum are the old dead 
leaves, diseased the previous season, or overwintered living leaves in which ~ 
the pathogene has hibernated. 
Pathogenesis. ‘The inoculum consists of the sporidia. These 
are formed on the promycelium which develops from the teliospore. 
Teliospores which are produced late in the autumn often do not germinate 
at once but remain dormant on the old dead leaves. More commonly, 
however, late infections on immature green leaves of the hollyhock or on 
those of Malva rotundifolia do not develop telia until early spring. The 
teliospores in these telia germinate and sporidia for the primary infections 
are formed. 
Study germinating teliospores; or illustrations in Phytopath. 1, pl. 
XIII. oBSERVE:— 
10. The long slender basidium (promycelium}, most commonly 
- developed first from the apical cell. 2 
11. The densely granular protoplasm of the apical portion 
of the basidium; its final division into four cells, and the formation of a 
sporidium from each. 
12. That sometimes the four apical cells separate before sporidia 
are developed. 
Make a series of DRAWINGS to show sporidial formation. 
The sporidia are carried by the wind or splashing rain to the leaves 
nearby. Here they quickly germinate sending forth a short germtube 
which penetrates the host. 
DRAW several germinating sporidia. These sporidia are uninuculeate 
and develop within the host-tissues a septate uninucleate mycelium. 
Study thin sections (freehand or prepared) through a lesion. OBSERVE:— 
13. The slender, often matted, septate mycelium in the inter- 
cellular spaces or forcing the host-cells apart. Are haustoria formed? 
14. The matted mycelial stroma from which arise the slender 
teliospore-stalks, forming the telial sorus. 
15. The teliospores; form, size, color, septation and thickness 
of walls. 
16. Young spores in various stages of development. 
Make a detailed prawiNnc of a telial sorus in section with adjacent 
host-tissue and intercellular mycelium. 
The teliospores germinate in situ, giving rise to the sporidia which, 
scattered by wind or rain, initiate secondary cycles. 
Secondary Cycles are initiated repeatedly throughout the season 
and. conform in their development to that of the primary cycles except 
that in the case of late secondary cycles, teliospores, which have developed, 
may fail to germinate at once and overwinter on dead leaves and stems. 
Very late secondary cycles on overwintered living leaves may fail to 
develop telia until the following spring. 
