Arecoideae - Palm-ID

Arecoideae

Arecoideae Burnett

A specific description is here impossible to establish because of the numerous genera of this subfamily.

In this version only the Arecoideae that are identifiable with certainty are here described.

informative descriptor

general stem pattern (ex-von Mohl's classification) : Cocos-Type ; Mauritia-Type ; Geonoma-Type
shape of fibrous part in transverse section : Sagittata ; Reniforma to Cordata - Complanata
cortex : developed ; very thin
superficial protective layer (sub-epidermal) : permanent epidermis ; developed etagen meristem (alignment of more than 10 cells)
tangential elongation and anticlinal divisions of subcortical parenchyma cells : present ; absent
fibrous bundles in central cylinder : present ; absent
fibrous part adjacent to the xylem : present (often only in the central zone) ; absent
little fibrous vascular bundles (bridges) : ?
number of phloem strand : one strand throughout the central cylinder
radial elongation of the fibrous part (in subcortical zone) : strongly developed ; absent
radiating parenchyma : absent
ground parenchyma of the central cylinder : spheroid to slightly elongated (length / width < 3–4) cells (∅ < 150 µm) and compact [sometimes few and little lacunae in old stems ; cells slightly elongated (length / width < 3–4), lobed with a random (rhombohedral) shape (maximal length < 200 µm) and irregular meshwork (lacunae < 200 µm) ; rod-like cells (length > 200 µm; length / width > (3)–5) and more or less regular and large meshwork (lacunae > 250 µm) ; huge cells (∅ > 150 µm) [potential few and irregular lacunae] ; appendicular parenchyma connecting fvb
ground parenchyma sustained growth : absent (Type A) ; present (Type B)
phytoliths : globular echinate to granulate ; trapeziform to rondel (ex hat shaped)
number of wide metaxylem element per fibrous vascular bundle : mostly 1 ; 1 in the the subcortical zone and the zone of transition AND 2 in the central zone
tabular parenchyma : present ; absent
end wall slope : very oblique ; oblique ; slightly oblique
specialisation value : [1] multiple perforation plates with "pithlike" perforations that span ≤ 1 vessel-parenchyma pit on the adjacent lateral wall ; 1 to ≤ 2 vessel-parenchyma pits">[2] multiple perforation plates with "narrow" perforations that span >1 to ≤ 2 vessel-parenchyma pits ; 2 to ≤ 5 vessel-parenchyma pits">[3] multiple perforation plates with "medium size" perforations that span >2 to ≤ 5 vessel-parenchyma pits ; 5 vessel-parenchyma pits, or with ≤ 3 bars">[4] multiple perforation plates with "wide" perforations that span >5 vessel-parenchyma pits, or with ≤ 3 bars ; [5] mixture of multiples perforation plates (as in #4) and simple perforation plates ; [6] simple perforation plate only
multicellular epidermal hair : ?
epidermal cells : ?
wide metaxylem element : present
fibrous part centrifugal differentiation : present ; absent
metaphloem sieve plate : compound
phytoliths distribution in central cylinder : all around the fibrous part adjacent to the phloem throughout the central cylinder ; largely restricted to the fvb of the subcortical zone in contact with the cortex
identification within "subfamily" or "tribe" : in all palm family ; subfamily Arecoideae

cortex

central cylinder

fibrous vascular bundle

ground parenchyma

numerical

range of slope index (min_m_max) : 2,4 – 2,83 – 3,83

present in fossil descriptions but not informative