Describes the germination and early growth of Megarrhiza about which AG has been misinformed. The tubular petioles act functionally like a root.
Ipomoea did not germinate.
Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.
Jan 19. 80
My dear Gray,
I have been greatly interested with the Megarrhiza seeds which you so kindly sent me.
You have been misinformed about their germination, for I think you cannot have watched
the whole process Some were placed by me on, and others half an inch
beneath the surface, and others deeper, but none of the cotyledons were lifted up. One
seed on the surface was a little tilted by the root not penetrating the ground, but this
often occurs with all kinds of seeds. The petioles of my specimens were not stif enough
to bear the weight of the seed. What takes place is that the radicle bends down
& penetrates the ground, but grows only to a length of about half an inch or
less (length rather doubtful as I did not wish to kill specimens by making sections).
When of this length its growth is arrested, and the lower ends of the tubular petioles
grow quickly & penetrate the ground just like a root to a depth of nearly 2
It is has been a great grief to me that not one of the seeds of Ipomœa leptophylla has germinated: my gardener opened some & found them rotten. I hope I havn't wearied you much
Ever, my dear Gray, | Yours sincerely | Charles Darwin