Membranes of late endosomes and lysosomes contain V-class proton pumps that act in concert with Cl- channels to acidify the vesicle lumen.

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Secondary Growth in Roots

In the dicot root, the vascular cambium is completely secondary in origin.

It originates from the tissue located just below the phloem bundles, a portion of pericycle tissue

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TLS Online TPP Program

#Id: 10681

#XL - R Botany

TLS Online TPP Program

#Id: 10682

#XL - R Botany

Anomalous secondary growth

Several dicotyledons show secondary growth that is different from normal  secondary growth. The deviating methods of secondary thickening are called  abnormal or anomalous secondary growth. 

e.g., Bougainvillea (Dicot)

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#Id: 10683

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Dicot stem anomalous secondary growth occurs due to following reasons:

Anomalous position of cambium 

e.g.,Serjania sp. and Bauhinia sp.

Abnormal behavior of normal cambium

e.g., Bignonia, Aristolochia, Tinospora, Clematis etc.

Extrastelar cambium formation

e.g., Amaranthus sp. 

Interxylary phloem or included phloem

e.g., Entada sp (box bean), Combretum sp (Combretum), Strychnos sp.

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#Id: 10684

#XL - R Botany

Dicot stem anomalous secondary growth occurs due to following reasons:

Intraxylary phloem

Absence of vessels in the xylem

Scattered vascular bundles in dicot stem

Presence of medullary bundles

Presence of cortical bundles

Secondary growth in monocot

e.g., Dracaena