Arquivos de periódicos de maio 2021

10 de maio de 2021

Hakea sericea vs Hakea decurrens (revisited)

According to [1], this is how to identify Hakea sericea:

  • Shrub or small tree(!) up to 4 m (!), with an irregular canopy.
  • Leaves: evergreen, in the shape of a needle of 0,5-1,5 mm diameter, very robust(!), of 4-8 cm, extremely sharp, dark green to greyish-green.
    [Presumably this description applies only to adult plants.]

  • Flowers: white, bland, arranged in axillary fascicles of 1-7 flowers.
  • Fruits: woody follicles, dark brown, with a patent crest and beak, having two black, winged seeds.
  • Flowering: January to April.

(This description might be wrong: the features indicated with (!) actually seem match Hakea decurrens [5] more closely than Hakea sericea [4].)

Mr. Arthur D. Chapman kindly compared the descriptions of Hakea sericea and Hakea decurrens ssp. physocarpa from several sources and organized the information in several comparison tables. The resulting work can be consulted here:

Some months ago I also tried to contrast the descriptions of both species, from a couple of sources, and compared them with my own observations. In the following,

  • HS refers to Hakea sericea,
  • HDp refers to Hakea decurrens ssp. physocarpa,
  • (+) indicates features that I believe to have seen,
  • (-) for features that I believe not to have seen in the spiky Hakea plants around Lousã,
  • (?) indicates features that are not always present,
  • (??) indicates features that I have not yet confirmed (didn't see or don't remember),
  • (?!) for features whose description is obscure to me,
  • (!!) highlights features that are described differently in different sources,
  • (//) for features for which are indistinctive for both species.

Pistil / gynoecium

  • HS: (-)(4.5–) 5–7 (–7.5) mm long [6]
    HS: gynoecium (-)4–7.5 mm long [7]

  • HD: 8.5–12(+) mm long [6]
    HD: gynoecium 9–12(+) mm long [7]
    HDp: pistil (+)8.5–12.2 mm long [8]

Pedicels (!!)

  • HS: sparsely(??) white-pubescent(+) [4]
    HS: pedicel villous(??) to hirsute(??) [6]
    HS: pedicels villous(??), hairs white [7]

  • HD: pubescent(??) [5]
    HD: appressed(??) pubescent(??) [6]
    HD: tomentose(??) or appressed(??) pubescent(??), hairs white(+) and/or rust-brown(-) [7]
    HDp: pedicels 1.2–4.8(??) mm long [8]


  • HS: 4–5(??) mm long, white(+), glabrous(+) [4]
    HS: perianth (-)2.5–4.7 mm long [7]
    HS: perianth white(+) [6]
    HS: flowers white(+), pink in bud(+) [7]

  • HD: 4–7(+) mm long, white(+) or sometimes tinged pink(?), glabrous(+) [5]
    HD: 4.2–7.2(+) mm long [7]
    HD: perianth white(+) or pink(-) [6]
    HDp: perianth 4.2–7.2(+) mm long, glabrous(+) [8]
    HDp: white(+) to pink(-) flowers [8]


  • HS: usually simple(?!), mostly 3–8(??) mm long [4]
  • HD: knob-like(?!), [up] to 3(??) mm long [5]
    HDp: rachis simple(?!), 0.5–2.8(??) mm long, with tomentose(??) or appressed(??) white and/or ferruginous (-) hairs, extending onto pedicels(??) [8]

Young branches / branchlets (!!)

  • HS: young branches white(+)-pubescent(?!), glabrescent(+) [4]
    HS: branchlets persistently woolly(-) tomentose(-) [7]

  • HD: new growth glabrous to sparsely(+) or densely(-) hairy [5]
    HD: branchlets quickly glabrescent(+) or persistently(-) and densely(-) tomentose [7]
    HDp: branchlets sparsely(+) to densely(-) appressed-sericeous, quickly glabrescent(+) or persistent to flowering [8]

Leaves (!!)

  • HS: leaves ± at right angles(+) to stem [4]
    [Presumably this applies only to old branches in adult plants.]
    HS: leaves spreading widely(+) to narrowly(+) angled to stem, flexible(+) or rigid(+) [6]
    [In Lousã, all plants less than 3 years old - especially those growing in shaded areas - have flexible branclets and very flexible leaves narrowly angled to stem. This also applies to new branches in slightly older plants, perhaps up to 1.5m high.]

  • HD: leaves spreading widely(?) from stem [5]
    HD: leaves spreading widely(?) from stem, rigid(?) [6]
    HDp: leaves widely spreading, grooved below(?!) to varying extents, 1.5–8(+) cm long, 0.7–1.6(+) mm wide, rapidly glabrescent(??)
    [I never saw any hairy leaves, only hairy branchlets, therefore "glabrescent leaves" doesn't seem to apply.]

"Decurrens has smoother(+) fruit than sericea which is tubercular(?!) to deeply wrinkled(-)." [10]
"Fruit on decurrens is narrower(-) and has a prominent beak(+) with two horns(+) but are often eroded. Sericea is broadly ovoid(+) and horns are often obscure(-)." [10]

  • HS: ± globose(+) to ovoid, 25–30(//) mm long, 20–25(//) mm wide, deeply wrinkled(-), beak 3–4(+) mm long, ± smooth(-) [4]
  • HD: ± ovoid, 18–35(//) mm long, 14–36(//) mm wide, covered in discrete warts(+); beak prominent(?!); horns present(+) [5]
    HDp: fruit 2.1–3.2(//) cm long, (-)1.3–2.5 cm wide, finely or coarsely tuberculate(+), obliquely(-) ovate to broadly ovate(-) [8]
    HDp: beak small(+) to moderately large, sparsely pustulate or smooth [8]
    HDp: horns (+)1–5 mm long [8]


  • HS: not lignotuberous(+) [6]
  • HD: lignotuber present(-) [5]
    HD: lignotuberous(-) [6]

Mucro (!!)

  • HS: 1-3mm(+) long [4]
  • HD: 1mm long [5]
    HDp: apex porrect(?!), with mucro 1–3.5(+) mm long [8]

Overall aspect:
"Sericea appears much denser(+) than decurrens." [10]

  • HS: spreading bushy(+) shrub 1–3 m(+) high [4]
  • HD: spreading shrub(//) to small tree 0.3–5(-) m high [5]
    HDp: small tree or shrub, 0.8–5(-) m tall [8]


  • HS: (...) on the coast(-) and adjacent ranges [4]
  • HD: (...) often grows in sandy(-) or rocky(+) situations [5]
    HDp: found in eucalypt(+) forest, damp heath(+) or dry scrubland in hilly(+) areas in sand(-), clay(-), granite(-), basalt(-) or sandstone(?!), from sea-level to 300(?) m [8]
    [Our spiky Hakea trees are present at least 500 meters above sea level.]
    HDp: (...) also in Portugal [9]


  • Adventitious: produced in an unpredictable or unusual position [2]
  • Appressed: pressed closely but not fused, e.g. leaves against a stem [2]
  • Apex: the tip; the point furthest from the point of attachment [2]
  • Bland: mild, smooth, gentle
  • Bud: a compact growth on a plant that develops into a leaf, flower, or shoot
  • Bushy: growing thickly
  • Axillary: coming from the leaf's axil, i.e. the insertion of the leaf [2]
  • Carpel: the basic female reproductive organ in angiosperms, either consisting of a single sporophyll (?!) or a single locule of a compound ovary, with a style and a stigma [2]
  • Crest: a "ridge"
  • Fascicle: a cluster of flowers [2]
  • Follicle: a dry fruit formed from one carpel, splitting along a single suture... [2]
  • Gynoecium: the collective term for all of the carpels of a single flower [2]
  • Hirsute: bearing coarse, rough, longish hairs
  • Lignotuber: a woody swelling of the stem below or just above the ground; contains adventitious buds from which new shoots can develop, e.g. after fire [2]
  • Matted: (especially of hair, wool, or fur) tangled into a thick mass
  • Mucro: a sharp, short point, generally at the tip of a leaf [2]
  • Pedicel: the stalk of a flower [2]
  • Perianth: the collective term for the calyx and corolla of a flower (generally used when the two are too similar to be easily distinguishable) [2]
  • Pistil: 1. a single carpel when the carpels are free / 2. a group of carpels when the carpels are united by the fusion of their walls [2]
  • Porrect: extended forwards
  • Pubescent: covered with short, soft hairs, especially erect hairs [2]
  • Rachis: the axis of an inflorescence [2]
  • Shaggy: having a covering resembling rough, long, thick hair
  • Tomentum: a dense covering of short, matted hairs [2]
  • Tubercle: a small wart-like outgrowth or protuberance of tissue [2]
  • Tuberculate: covered in tubercles
  • Villous: abounding in or covered with long, soft, straight hairs; shaggy with soft hairs [2]
  • Wart: verruga in Portuguese
  • Woolly: very densely covered with long, more or less matted or intertwined hairs, resembling a sheep's wool [2]
  • Wrinkled: having wrinkles or slight folds

@belmontmargie: another person, with a lot of plant knowledge, says decurrens has smoother fruit than sericea which is tubercular to deeply wrinkled. Sericea appears much denser than decurrens. leaves in decurrens are widely spreading as in your photo. Fruit on decurrens is narrower and has a prominent beak with two horns but are often eroded. Sericea is broadly ovoid and horns are often obscure.

Posted on 10 de maio de 2021, 01:22 PM by mferreira mferreira | 0 comentários | Deixar um comentário

Hakea sericea vs Hakea decurrens: an attempt to find reliable observations on iNaturalist

Research Grade:

Without the RG requirement:
Significant overlap, with the same major difference:

  • around Sydney and all the way south to Canberra and Nowra: Hakea sericea but not Hakea decurrens physocarpa;
  • between the Wilsons Promontory and Cape Howe: Hakea decurrens physocarpa but not Hakea sericea.

Hakea decurrens (any subspecies), Research grade:

  • some scattered observations around Sydney and Camberra;
  • more observations in the SE, where there are no RG observations of Hakea sericea.

Places where only Hakea sericea is found:

Places where only Hakea decurrens is found:

Some RG observations of Hakea sericea in the Greater Sydney Area with more than 2 IDs:

Some RG observations of Hakea decurrens physocarpa in E. Gippsland - Orbost / South Gippsland - East / Wellington - Alberton (never with more than 2 IDs):

Judging from these observations, reinforced by those from South Africa, I still think that the species observed around Lousã is probably Hakea sericea rather than Hakea decurrens ssp. physocarpa. The leaves are not always perpendicular to the stem, quite the contrary, as can be seen in these observations (among many others):

Posted on 10 de maio de 2021, 05:13 PM by mferreira mferreira | 0 comentários | Deixar um comentário