Size of stomata and palisade parenchyma on cotyledon adaxial side in someBrassica oleracea L. varieties
Cotyledons of 15 day-old seedlings of fiveBrassica oleracea L. varieties were surveyed to identify salient anatomical features. Both palisade parenchyma cells present in the first subepidermal layer and stomata were found to differ in size.
Development of Stomata in Some Cruciferae
Epidermal structure and ontogeny of stomata are described for ten species or varieties of Cruciferae. The mature stomata are typically anisocytic. Their development is of the mesogenous trilabrate type. The spiral sequence of divisions in the meristemoid may be clockwise or anticlockwise. Very often the neighbouring cells divide and form successive generations of stomata which become arranged in groups. Some theoretical implications of the study are also discussed.
Root Formation by Detached White Mustard (Sinapis alba) Cotyledons
Rooting is shown to occur in excised cotyledons of Sinapis alba when grown in petri dishes on moist filter paper. Cotyledons were excised at intervals from 6 hours after the start of imbibition, when they were yellow, unexpanded and enclosed within the testa, to 27 days after sowing when the cotyledons were green and fully expanded and on plants possessing up to 3 foliage leaves. Rooting generally began 5 or 6 days after excision and was completed dining the following 5 days. The age of cotyledons at t ho time of excision had three effects on rooting: the lag period be-fore rooting began and the period during which rooting took place both increased with age: but the most marked effect was on the total number of cotyledons which were able to form roots, which increased until cotyledon expansion was almost complete, then decreased as the mature cotyledons became older. Optimal rooting was shown by cotyledons detached 8 days alter sowing, when they were half expanded. At this age S5 % of them formed roots between 6 days and 8 days after excision.