W.L.H. van Veenendaal

Development of included phloem and organization of the phloem network in the stem of Strychnos millepunctata (Loganiaceae).

The development of the diffuse included phloem strands in Strychnos millepunctata Leeuwenberg is described and compared with that in some other Strychnos species.

Development of included phloem in the stem of Combretum nigricans (Combretaceae)

The development of diffuse included phloem strands in Combretum nigricans sterns is described, During a short period of time, a small phloem strand is cut off locally in an inward direction by an otherwise normal bidirectional vascular cambium. This contrasts with previous descriptions and interpretations because these strands are not formed after redifferentiation of secondary xylem parenchyma. A complementary cambium formed at the inner border of the young strand somewhat enlarges the strand and, during a relatively long period, produces secondary phloem outwards. Finally this complementary cambium stops functioning as a cambium and merges with the secondary phloem it has produced. Radial rows of cells are present within the included phloem strands which continue into the later-formed secondary xylem; rays transverse the strands. Crushing of the phloem takes place near the outer border of the strand, forming cap-like tissues of disorganized cells.

Wood Anatomy of the Baphia Group (Leguminosae)

The secondary xylem of 5 of the 6 genera belonging to the Baphia-group (viz. Airyantha, Baphiastrum, Leucomphalos, Dalhousiea and Baphia) and Ormosia (Leguminosae-Papilionoideae- Sophoreae) was studied, in order to aid generic delimitation in the Baphia-group.

Gold speckles and crystals in tomato fruits (Lycopersicon esculentum Mill.).

SummaryTomato fruit walls often possess tiny yellowish spots around the calyx and shoulders of the fruit, so-called gold speckles. In some cases these become very numerous and lead to down-grading of the fruit. In such fruit crystal sand is present in separate cells and groups of cells in the outermost parenchymatous tissue layers of the mesocarp. This crystal sand causes the gold speckles. Also raphid crystals occur in great quantities in the pulp of those tomatoes which display numerous gold speckles in the wall. Druse crystals are absent. Both crystal sand and raphid crystals proved to be organic calcium salts, probably calcium oxalate. Silicon was associated with the crystal sand containing cells of the mesocarp, either as very small silica grains in the cell or randomly distributed in the cell wall as in normal cells. The long raphid crystals may perforate neighbouring parenchyma cells during picking and transporting of the fruit and hence limit its storage life-time. Nutrient substances used in subs...

Wood anatomy of the Aphanocalyx-Monopetalanthus complex (Caesalpinioideae).

The secondary xylem of 3 of the 4 genera belonging to the Aphanocalyx-Monopetalanthus complex (Aphanocalyx, Monopetalanthus and Tetraberlinia; from Michelsonia no samples were available) and the closely related genera Julbernardia and Brachystegia was studied in order to aid generic delimitation.