Prosartes lanuginosa - old stem question

Laura & Dave
Sun, 09 Dec 2012 13:25:22 PST
Hi All
   I've been doing some very tardy repotting of some older plants (tardy both in 
years and season, I'm afraid).  The Prosartes (Disporum) lanuginosa have been in 
the same pot for about 10 years.  When I unearthed it, there were three or four 
terminal shoots, and many inches of rhizome from previous years, with an 
inverted forest of roots for their whole length, many of which don't appear 
dead.  Unlike Trillium, which seem to allow the oldest parts of the rhizome to 
rot away after so many years, the Prosartes I know (lanuginosa, and our native 
hookerii and smithii) all seem to keep the old rhizome around.  Repotting 
plants, with these old tangled root masses requires a large pot, and lots of soil.
   My question is whether these old parts are really contributing to the growth 
of the plant?  They appear to be very woody, so that they wouldn't be much good 
for food storage.  And transport of water, nutients and gasses I would think 
would also be impeded. It's interesting to be able to trace the path the 
rhizomes have taken over the years, but not too helpful.
   I'm thinking of cutting the old parts away when repotting, leaving a 2" to 3" 
piece to pot.  If I'm correct in my guess about the life stage of the older 
parts, I'm guessing that they wouldn't have the energy to initiate side shoots 
(but I'd try a few just to find out, of course).

   What do others think, or have experience with.

   Dave Brastow  ...  Tumwater, Washington (USA)

P.S.  Wow!! My first flower ever of Zephyranthes macrosiphon opened this 
morning!  Many thanks again to all for the wonderful seed/bulb exchange, and the 
PBS as a whole.

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